Silica-supported Fe/Fe–O nanoparticles for the catalytic hydrogenation of nitriles to amines in the presence of aluminium additives

A icles h ps://doi.o g/10.1038/s41929-021-00722-x 1Leibniz-Ins i u ü Ka alyse e.V., Ros ock, Ge many. 2Regional Cen e o Ad anced Technologies and Ma e ials, Czech Ad anced Technology and Resea ch Ins i u e, Palacky Uni e si y Olomouc, Olomouc, Czech Republic. 3Nano echnology Cen e, Cen e o Ene gy and En i onmen al Technologies, VŠB– Technical Uni e si y o Os a a, Os a a-Po uba, Czech Republic. 4Depa men o Indus ial and Enginee ing Chemis y, Ins i u e o Chemical Technology Mumbai-Ma a hwada Campus, Jalna, Maha ash a, India. ✉e-mail: [email p o ec ed]; mb.g[email p o ec ed].edu.in; jagadeesh. [email p o ec ed]; [email p o ec ed] Ca alysis plays a decisi e ole in many basic and applied chemical p ocesses and is in ol ed in he indus ial p o- duc ion o mo e han 90% o ine and bulk chemicals as well as polyme ic ma e ials and many o he e e yday p oduc s1–5. In addi ion, he syn hesis o bioac i e compounds o li e sciences and he success o sus ainable ene gy echnologies, including g een uels, depend on e icien ca aly ic p ocesses1–5. Indeed, he suc- cess o o ganic syn hesis in he las 100 yea s elied o a la ge ex en on he disco e y and applica ion o sui able ca alys s1–5. In his espec , speci ically, he de elopmen o p ac ical and cos -e icien hyd ogena ion s a egies cons i u es a key achie emen o he las cen u y6. Nowadays, a ple ho a o molecula ly de ined me al com- plexes as well as he e ogeneous ma e ials a e equen ly applied o he selec i e hyd ogena ion o alkynes7,8, ole ins7,9,10, ca bonyl com- pounds11,12, ni oa enes13,14 as well as (he e o)a enes7,15–17. Among hese hyd ogena ion eac ions, he ans o ma ion o ni iles o p i- ma y amines is pa icula ly aluable because he la e p oduc s a e p i ileged compounds in chemis y, medicine and biology18–22. In gene al, p ima y amines cons i u e impo an p ecu so s and cen- al in e media es in he chemical, pha maceu ical, ag ochemical and ma e ials indus ies18–22. A e he o iginal disco e y o benzo- ni ile hyd ogena ion in he p esence o nickel in 1905 ( e . 23), many ca alys s we e de eloped o his and ela ed eac ions (Fig. 1)24–42. These achie emen s we e mainly possible due o he design o p e- cious me al sys ems, which allow eac ions o be pe o med a low empe a u e and p essu e24,30,31,33–38. Howe e , despi e hei emen- dous success, hei limi ed a ailabili y and highe p ice cons i u e majo d awbacks. Thus, s a e-o - he-a ca alys s o ni ile hyd o- gena ion in indus y con inue o be Raney nickel26,27,31,33 and coppe ch omi e29, which demand ha sh condi ions and su e om oxici y issues. To sol e hese p oblems, al e na i e nickel- and cobal -based he e ogeneous ca alys s ha e been epo ed in ecen yea s35,39–41. F om a sus ainabili y poin o iew, i on would be an ideal ca a- lys sys em o ni ile hyd ogena ion because o i s abundance (a 4.7% i is he second-mos abundan me al in he ea h c us ), low p ice and low oxici y14,17,42–44. Indeed, in he las decade, using sophis ica ed/syn he ically demanding PNP pince ligands, ac i e i on complexes ha e been de eloped o hyd ogena e ni iles44. In gene al, howe e , hese me al complexes a e less s able and di icul o use. In con as , he e ogeneous ca alys s show imp o ed s abili y and can be easily eused14,17,22,45–47. Un o una ely, o he bes o ou knowledge, analogous suppo ed ac i e i on cen es o he hyd o- gena ion o ni iles ha e no been c ea ed ye . He e, we epo a s able and con enien i on-based nanoca alys ob ained by he py olysis o i on ace a e on comme cial silica ha shows excellen ac i i y and selec i i y o he hyd ogena ion o a la ge numbe o ni iles o p oduce p ima y amines in he p esence o ca aly ic amoun s o aluminium addi i es. Resul s Syn hesis and cha ac e iza ion o Fe-based nanoca alys s. In he las decade, he excellen ca aly ic pe o mance o ca bon-encapsula ed co e–shell 3d me al nanopa icles has been demons a ed in a a ie y o hyd ogena ion eac ions14,16,17,22,39,40,46. These ca alys s we e p epa ed by he immobiliza ion and py oly- sis o me al complexes o me al o ganic amewo ks on ino ganic suppo s ( o example, ca bon, SiO2 and Al2O3)14,16,17,22,39,40,46. In his con ex , we de eloped ac i a ed Fe2O3 nanopa icles, su ounded by Silica-suppo ed Fe/Fe–O nanopa icles o he ca aly ic hyd ogena ion o ni iles o amines in he p esence o aluminium addi i es Vishwas G. Chand ashekha    1, Thi usangumu ugan Sen hama ai1, Ra ishanka G. Kadam   2, Ondřej Malina2, Jose Kašlík   2, Radek Zbořil   2,3 ✉ , Manoj B. Gawande   2,4 ✉ , Rajenahally V. Jagadeesh   1 ✉ and Ma hias Belle    1 ✉ The hyd ogena ion o ni iles o amines ep esen s an impo an and equen ly used indus ial p ocess due o he b oad appli- cabili y o he esul ing p oduc s in chemis y and li e sciences. Despi e he exis ing po olio o ca alys s epo ed o he hyd ogena ion o ni iles, he de elopmen o i on-based he e ogeneous ca alys s o his p ocess is s ill a challenge. He e, we show ha he imp egna ion and py olysis o i on(II) ace a e on comme cial silica p oduces a eusable Fe/Fe–O@SiO2 ca alys wi h a well-de ined s uc u e comp ising he ayali e phase a he Si–Fe in e ace and α-Fe nanopa icles, co e ed by an ul a- hin amo phous i on(III) oxide laye , g owing om he silica ma ix. These Fe/Fe–O co e–shell nanopa icles, in he p esence o ca aly ic amoun s o aluminium addi i es, p omo e he hyd ogena ion o all kinds o ni iles, including s uc u ally challeng- ing and unc ionally di e se a oma ic, he e ocyclic, alipha ic and a y ni iles, o p oduce p ima y amines unde scalable and indus ially iable condi ions. NaTuRe CaTalySiS | VOL 5 | JANUARY 2022 | 20–29 | www.na u e.com/na ca al 20 A icles NaTu e CaTalySIS ni ogen-doped g aphene, as selec i e ca alys s o he hyd ogena- ion o ni oa enes o anilines14. In addi ion, suppo ed Fe-based nanopa icles ha e also been ound ac i e o he hyd ogena ion o quinolines17. Howe e , hese and ela ed Fe ma e ials showed no ac i i y o mo e challenging subs a es, including ni iles (Supplemen a y Table 1, en ies 1 and 2). To iden i y po en ial i on-based he e ogeneous ca alys s o ni ile hyd ogena ion, we p epa ed a se ies o i on nanopa icles suppo ed on a ious sup- po s. Speci ically, comme cially a ailable neu al, acidic and basic ino ganic suppo s, o example, Vulcan XC72R ca bon powde , Ae osil silica (SiO2), γ-Al2O3 and MgO, we e imp egna ed wi h i on(II) ace a e. Subsequen ly, hese ma e ials we e py olysed a 800 °C unde educ i e (H2) condi ions. A schema ic illus a ion o he syn he ic p ocedu e wi h he SiO2 suppo is p esen ed in Fig. 2. He ea e , hese ma e ials a e deno ed as Fe(OAc)2-suppo -x, whe e x deno es he py olysis empe a u e. As a benchma k eac ion, he hyd ogena ion o 4-chlo obenzoni ile (1) o 4-chlo obenzylamine (2) was chosen (Fig. 3), no only o iden i y an ac i e ca alys sys em, bu also a selec i e one. No ably, 1 easily unde goes educ i e dehalogena- ion in he p esence o many known hyd ogena ion ca alys s. To ou su p ise, du ing ini ial con ol expe imen s, we obse ed some ac i i y (26% yield o 2) and high selec i i y (>90%) o he p ima y amine in he p esence o Fe(OAc)2-SiO2-800 (Fig. 3). To imp o e he con e sion and yield, we a ied he eac ion condi ions ( empe a u e, sol en , ca alys loading) and in es iga ed he in lu- ence o addi i es (Supplemen a y Tables 1–3). Applying highe ca alys loadings (up o 12.8 mol%), he p oduc yield inc eased up o 50%, and he selec i i y o he p ima y amine emained e y good. G a i yingly, in he p esence o aluminium iisop opoxide, he yield o 4-chlo obenzylamine (2) d ama ically inc eased o 96%. Following his excellen esul , se e al o he me al alkoxides, alu- minium compounds as well as Lewis acids and bases we e es ed as addi i es (Supplemen a y Table 2). Su p isingly, only a ew addi- i es, o example, p- oluenesul onic acid, showed a posi i e e ec on he eac ion, while mos , o example, bases, had a nega i e impac . Op imal esul s, wi h an almos quan i a i e yield o 2, we e achie ed in he p esence o inexpensi e aluminium oil (Fig. 3 and Supplemen a y Fig. 1). In his case, he aluminium oil comple ely dissol ed in he sol en (isop opanol), which explains he simila posi i e e ec o aluminium oil and aluminium iisop opoxide. Con ol expe imen s p o ed ha his dissolu ion only akes place in he p esence o ammonia (Supplemen a y Table 4). To elucida e he c ucial ole o aluminium addi i es, we pe o med kine ic in es iga- ions o he model eac ion in he absence and p esence o aluminium oil and aluminium iisop opoxide (Supplemen a y Figs. 2 and 3). Su p isingly, all he eac ions needed a p eac i a ion ime (3–9 h) o s a . Only in he p esence o aluminium iisop opoxide was his p eac i a ion d as ically educed. Based on hese esul s and he es ing o he di e en addi i es, we assume ha bo h aluminium (2016 onwa ds) Suppo ed Co and Ni NPs de i ed om me al complexes and MOFs 1905 (1905) Ni (1909) Colloidal Pd (1923) Raney Ni (1925) P O2 Cu2C 2O5 (1937) (1937) Raney Co Suppo ed ca alys s (Rh, Pd, P , Ru, Ni, Co) (1946 onwa ds) (A ound 1969) Me al bo ides (RhB, P B, RuB, NiB, CoB) Me al alloys (PdNi, NiAl, NiCo) (A ound 1970) His o y o ni ile hyd ogena ion using he e ogeneous ca alys s o e a cen u y 2021 Fe/FeÐO@SiO2 This wo k Fig. 1 | His o ical o e iew o he e ogeneous ni ile hyd ogena ion ca alys s. The hyd ogena ion o ni iles using he e ogeneous ca alys s has a long his o y ha co e s mo e han a cen u y. Fe(OAc)2 Fe FeO FeII immobilized on SiO2 Py olysis 1. S i , DMF, 150 ¡C 2. Addi ion o SiO2 3. S i , DMF, 150 ¡C, 4 h 4. Slow e apo a ion o DMF and d ying 800 ¡C, 4 h, H2 Fe/FeÐO co eÐshell nanopa icles suppo ed on SiO2 Fig. 2 | Ca alys p epa a ion. Syn hesis o Fe/Fe–O co e–shell nanopa icles by he imp egna ion and py olysis o i on(II) ace a e on SiO2. DMF, N,N-dime hyl o mamide. NaTuRe CaTalySiS | VOL 5 | JANUARY 2022 | 20–29 | www.na u e.com/na ca al 21 A icles NaTu e CaTalySIS iisop opoxide and aluminium oil a e con e ed unde he eac- ion condi ions o an ac i e Lewis acid co-ca alys ha ac i a es he ni ile g oup. These Lewis acidic cen es can p obably also be gene - a ed on he silica suppo close o he nanopa icles by eac ion wi h Si–OH si es on he su ace. No ably, ca aly ic (subs oichiome ic) amoun s (20 mol%) o he aluminium addi i es we e su icien o achie e imp o ed yields. Unde he op imized condi ions, o he suppo ed ca alys s, such as Fe(OAc)2-C-800, Fe(OAc)2-Al2O3-800 and Fe(OAc)2-MgO-800 (Supplemen a y Figs. 4–6), did no show any ac i i y (Fig. 3). In hese samples we did no obse e needle-like well-de eloped α-Fe nanopa icles g owing om he ma ix, as we did in he case o he op imal ca alys , Fe(OAc)2-SiO2-800. In con as , he i on nanopa - icles we e highly agg ega ed and/o encapsula ed wi hin he ma ix (Supplemen a y Figs. 4–6). Simila ly, Fe(OAc)2 on SiO2 py olysed a 400 °C (Fe(OAc)2-SiO2-400) was comple ely inac i e (Fig. 3). This is explained by a no ully de eloped ac i e Fe nanos uc u e a low py olysis empe a u e, which is e iden om he powde X- ay di ac ion (PXRD) pa e n (Supplemen a y Fig. 7) and ansmis- sion elec on mic oscopy (TEM) image (Supplemen a y Fig. 8) o he Fe(OAc)2-SiO2-400 sample. By con as , Fe(OAc)2-SiO2-600 and Fe(OAc)2-SiO2-1,000 exhibi ed compa able ac i i ies o ha o Fe(OAc)2-SiO2-800, p o iding 93 and 94% yields o he desi ed p oduc , espec i ely. This co ela es well wi h he simila size and well-de eloped co e–shell s uc u e o he Fe(OAc)2-SiO2-600 and Fe(OAc)2-SiO2-1,000 samples (see he TEM images in Supplemen a y Figs. 9 and 10) compa ed wi h Fe(OAc)2-SiO2-800 (Fig. 4c). As expec ed, i on(II) ace a e, unpy olysed Fe(OAc)2-SiO2 and Al addi i es alone we e comple ely inac i e in he eac ion (Fig. 3). Addi ionally, we p epa ed con ol samples, including pu e amo phous Fe2O3 nanopa icles (NPs), ayali e (Fe2SiO4) NPs and ma ix- ee Fe–Fe2O3 co e–shell NPs wi h a e y hin oxidic shell (Supplemen a y Figs. 11–13), and in es iga ed hei pe o mance in he model eac ion. No ably, he ayali e and Fe2O3 NPs we e comple ely inac i e, whe eas he Fe–Fe2O3 co e–shell NPs ga e 30% yield (Supplemen a y Table 5, en ies 1–3). This con i med he c ucial ole o he Fe–Fe2O3 co e–shell supe s uc u e in igge ing he ca aly ic p ocess. We belie e ha he ac i e ma e ial in ol es Fe cen es and/o he Fe–O a omic in e ace48. The high ac i i y o he ca alys inco po a ing he SiO2 ma ix (Fe(OAc)2-SiO2-800) s ongly indica es ha he ma ix egula es he size o he i on oxide c ys alli es49,50. Indeed, i has al eady been epo ed ha he Cu–O– SiOx in e ace in a silica-suppo ed coppe (Cu@SiO2) ca alys plays a key ole in H2 dissocia ion o o m Cu–Hδ− and SiO–Hδ+ species51. Thus, we belie e ha he silica in Fe(OAc)2-SiO2-800 would con- ibu e o he ca aly ic ac i i y by o ming such an ac i e me al–sup- po (Fe–O–SiOx) in e ace. Nex , we conduc ed a de ailed cha ac e iza ion o he mos ac i e ca alys Fe(OAc)2-SiO2-800. TEM analysis e ealed he o ma ion o co e–shell s uc u es wi h globula and od-shape mo phologies, wi h he needle diame e s anging om 10 o 30 nm and leng hs up o 100 nm (Fig. 4a–c). Ene gy-dispe si e X- ay spec oscopy (EDS) o his ma e ial showed he p esence o Si, O and Fe ele- men s (Supplemen a y Fig. 14). The high- esolu ion TEM image (HRTEM; Fig. 4d) con i ms ha he me allic pa o he ca alys is composed o an α-Fe co e g owing om he SiO2 ma ix. Indeed, he high-angle annula da k- ield scanning ansmission elec- on mic oscopy (HAADF-STEM) and elemen al mapping images clea ly e i y ha he Fe co e nanopa icles a e g owing om he SiO2 ma ix and a e co e ed by a laye o ul a hin i on oxide wi h a hickness o a ew nanome es (Fig. 4 –i). Based on his assignmen , he mos ac i e Fe(OAc)2-SiO2-800 ca alys is abb e ia ed o Fe/ Fe–O@SiO2 in he ollowing ex . A ep esen a i e HAADF-STEM image o a globula pa icle and ypical dep h p o ile plo showing he in ensi y dis ibu ion o he Si, O and Fe elemen s a a ious dis ances om he su ace a e shown in Fig. 5a,b, espec i ely. The dep h p o iles con i m ha he hickness o he oxidic Fe-O shell is less han 5 nm. Clea ly, he ca alys su ace is composed o i on nanopa icles, which g ow om he SiO2 ma ix, s abilized by an ex emely hin i on oxide shell. Fu he mo e, we pe o med e y de ailed chemical mapping wi h a ocus on he i on-con aining su ace componen s ha a e esponsible o he ca aly ic ac i i y. All he iden i ied Fe-bea ing su ace-ac i e phase was composed o Fe nanopa icles co e ed wi h a e y hin shell o i on oxide, i espec i e o he size and mo phology (globula , needle-like) o he Fe NPs (Supplemen a y Fig. 15). To iden i y he chemical and s uc u al cha ac e o he ca a- lys , we analysed he Fe/Fe–O@SiO2 sample by PXRD, Mössbaue spec oscopy, X- ay pho oelec on spec oscopy (XPS) and elec on pa amagne ic esonance (EPR) spec oscopy. The PXRD pa e n o Fe/Fe–O@SiO2 (Supplemen a y Fig. 16) shows s ong me allic α-Fe e lec ions a 2θ = 52.33, 77.16 and 99.60°, co esponding o c ys alline ace s o he Fe (110), (200) and (211) planes, espec- i ely (Join Commi ee on Powde Di ac ion S anda ds (JCPDS) ca d numbe 04-012-6482). Thus, α-Fe is he dominan c ys alline phase in ol ed in he ca alys supe s uc u e. The low-c ys alline SiO2 ma ix is ep esen ed by a b oad peak a 2θ ≈ 26°, indica ing he p esence o poo ly c ys alline c is obali e (JCPDS ca d num- be 04-008-7643). The ul a hin i on oxide laye is, in acco d wi h expec a ion, no iden i iable in he PXRD pa e n due o i s mos ly amo phous na u e. Howe e , de ailed PXRD analysis clea ly showed addi ional low-in ensi y di ac ion peaks co esponding o ayali e (Fe2SiO4, JCPDS ca d numbe 04-002-3681) and c ys alline silicon (Si(0), JCPDS ca d numbe 04-014-8844). In summa y, PXRD p o- ided a complex pic u e o he high- empe a u e chemis y o he Fe–Si–O sys em. These obse a ions a e in line wi h he XPS analysis, which con i med he p esence o jus Fe, Si and O elemen s in he su ey spec um (Supplemen a y Fig. 17a). The high- esolu ion O1s spec- um o Fe/Fe–O@SiO2 (Supplemen a y Fig. 17b) iden i ies peaks 26% 50% 96% 97% <1% <1% <1% <1% 94% 93% <1% <1% <1% 0 10 20 30 40 50 60 70 80 90 100 Yield o 4-chlo obenzylamine (%) Ca alys Fe(OAc)2-SiO2-800 Fe(OAc)2-SiO2-800 + AI(i-OP )3 b Fe(OAc)2-SiO2-800 + AIc Fe(OAc)2-C-800 + AIc Fe(OAc)2-Al2O3-800 + AIc Fe(OAc)2-MgO-800 + AIc Fe(OAc)2-SiO2-400 + AIc Fe(OAc)2-SiO2-600 + AIc Fe(OAc)2-SiO2-1000 + AIc Fe(OAc)2-SiO2 + AIc Fe(OAc)2 + AIc AIc Fe(OAc)2-SiO2-800a Fe ca alys N Cl Cl NH2 50 ba H2, 5–7 ba NH3 i-P OH, 120 °C, 24 h Fig. 3 | e alua ion o Fe ca alys s. Hyd ogena ion o 4-chlo obenzoni ile. Reac ion condi ions: 0.5 mmol 4-chlo obenzoni ile, 40 mg ca alys (8.5 mol% Fe), 50 ba H2, 5–7 ba NH3, 3 ml i-P OH, 120 °C, 24 h. Gas ch oma og aphy (GC) yields a e gi en using n-hexadecane as s anda d. aWi h 60 mg ca alys . bWi h 20 mol% Al(i-OP )3. cWi h 20 mol% (3 mg) Al oil. NaTuRe CaTalySiS | VOL 5 | JANUARY 2022 | 20–29 | www.na u e.com/na ca al 22 A icles NaTu e CaTalySIS a 530.72 and 533.14 eV, co esponding o Fe–O and Si–O bonds, espec i ely. Mos impo an ly, he high- esolu ion Fe2p spec- um (Supplemen a y Fig. 17d) e eals Fe 2p3/2 peaks a 710.27 and 712.73 eV, and Fe2p1/2 peaks a 723.37 and 725.83 eV, which can be asc ibed o Fe3+ species52, along wi h wo sa elli e peaks a 717.41 and 730.51 eV. This is s ong p oo ha he amo phous i on oxide phase co e ing he Fe(0) co e co esponds o amo phous Fe2O3. The o ma ion o i on(III) oxide was con i med by he hype ine pa am- e e s de i ed om oom- empe a u e Mössbaue spec oscopy (Fig. 5c). The 57Fe Mössbaue spec um o he sample shows a dominan sex e (68% o he ela i e spec um a ea) and wo double compo- nen s. Acco ding o he Mössbaue hype ine pa ame e s, he sex e wi h ze o isome shi and a hype ine ield o 32.9 T can be unam- biguously assigned o e omagne ic α-Fe. The double wi h high isome shi (1.18 mm s–1) and quad upole spli ing (2.64 mm s–1) clea ly belongs o Fe(II) ions in he ayali e s uc u e o med a he Si–Fe in e ace53, in pe ec ag eemen wi h he esul s o he PXRD measu emen s. Finally, he double wi h an isome shi o 0.35 mm s–1 is ypical o high-spin Fe(III) in amo phous i on(III) oxide wi h diso de ed symme y o he i on en i onmen , as p o ed by he ela i ely high quad upole spli ing (1.31 mm s–1)54. I is wo h men ioning ha possible aces o Fe(III) ions usually in ol ed in he ayali e s uc u e would o e lap he double o he i on(III) oxide phase. Finally, he EPR spec um o Fe/Fe–O@SiO2 shows b oad aniso opic signals wi h g ac o alues o gx = 2.72, gy = 2.04 and gz = 1.8 (ga e = 2.19) a 77 K (Fig. 5d), which indica es he p es- ence o e omagne ic pa icles co esponding o Fe(0) wi h dis inc size and mo phology. In summa y, HRTEM, HAADF-STEM, XPS, PXRD, EPR and Mössbaue spec oscopy allowed us o explo e he chemical and s uc u al cha ac e o he Fe/Fe–O@SiO2 ca alys , being composed o a SiO2 ma ix, a ayali e in e ace (Fe2SiO4) and α-Fe–amo phous Fe2O3 co e–shell nanopa icles g owing om he silica ma ix and ep esen ing he su ace-ac i e phase pa icipa ing in he ca aly ic p ocess. The EPR and Mössbaue da a con i m he e omagne ic cha ac e o he sample, p ede e mining he ca alys o simple magne ic sepa a ion. Hyd ogena ion o benzoni iles and he e ocyclic ni iles. Wi h an ac i e Fe-based ca alys (Fe/Fe–O@SiO2) in hand, we demons a ed i s gene al applicabili y o he selec i e hyd ogena ion o all kinds o ni iles. Al hough in mos o he eac ions aluminium oil was used as an inexpensi e addi i e, expe imen s pe o med o com- pa ison in he p esence o aluminium iisop opoxide ga e simila p oduc yields. Fi s , we ca ied ou he hyd ogena ion o a se ies o a oma ic ni iles (Fig. 6). Simple benzoni iles as well as subs i- u ed ones bea ing a oma ic o alkyl g oups ga e he co espond- ing p ima y amines in yields o up o 96% (Fig. 6, p oduc s 3–7). Fo he gene al applicabili y o any new ca alys , i s chemoselec i - i y is an impo an aspec . Thus, om a syn he ic poin o iew, i is impo an o no e ha his i on-based ca alys sys em is highly selec i e o he hyd ogena ion o he ni ile g oup in unc ionalized and mul isubs i u ed subs a es. As an example, amino-subs i u ed and halogena ed benzylic amines we e p epa ed, which a e e sa ile in e media es in o ganic syn hesis as well as o pha maceu icals and ag ochemicals. Such p oduc s, including he mo e sensi i e 4-iodobenzylamine, we e easily p oduced om he co esponding 200 nm 20 nm 20 nm 10 nm 10 nm 10 nm 10 nm 10 nm 5 nm abc de ghi Fe Fe Fe Fe O Si OSi HAADF Fig. 4 | TeM and HRTeM imaging o Fe(Oac)2-SiO2-800. a–i, TEM (a–c), HRTEM (d) and HAADF-STEM (e) images and elemen al mapping o i on ( ), i on and oxygen (g), i on and silicon (h), and i on, silicon and oxygen (i) o he Fe(OAc)2-SiO2-800 ca alys . NaTuRe CaTalySiS | VOL 5 | JANUARY 2022 | 20–29 | www.na u e.com/na ca al 23 A icles NaTu e CaTalySIS benzoni iles in yields o up o 97% (Fig. 6, p oduc s 8–16). In addi ion, i luo ome hyl-subs i u ed benzylamines we e ob ained in yields o 94 and 95% (Fig. 6, p oduc s 17 and 18, espec i ely). We we e also pleased o ind ha he ni ile g oup was also selec- i ely hyd ogena ed in he p esence o he mo e challenging C≡C, es e , bo onic es e , amide, e he , i luo ome hoxy and hioe he g oups (Fig. 6, p oduc s 19–30). Fu he mo e, when mul isubs i- u ed ni iles we e subjec ed o hyd ogena ion, educ ion o he CN g oup again ook place highly selec i ely owa ds he co esponding benzylic amines in yields o up o 95% (Fig. 6, p oduc s 31–46). He e ocyclic amines cons i u e e sa ile in e media es in he pha maceu ical and ag ochemical indus ies. In his espec , he selec i e hyd ogena ion o cyano-subs i u ed he e ocycles, o example, quinolines, indoles, py oles, benzodioxoles, benzodiox- anes, u ans, mo pholines and ph halanes, is o pa icula in e es . The co esponding he e ocyclic amines we e ob ained (excep o 3-cyano u an) in yields o 85–94% (Fig. 6). Hyd ogena ion o alipha ic ni iles. Compa ed wi h a oma ic ni iles, he hyd ogena ion o alipha ic ni iles is in gene al mo e challenging. Impo an ly, Fe/Fe–O@SiO2 exhibi ed high ac i i y and selec i i y o hese subs a es, including dini iles, unde iden ical condi ions (Fig. 7). Ini ially, se e al benzylic cyanides we e hyd o- gena ed o he co esponding p ima y amines in excellen yields (Fig. 7, p oduc s 57–72). In e es ingly, he 2-a yle hylamino mo i is a common sca old in many cen al ne ous sys em-ac i e com- pounds. He e, a a ie y o subs i u ed de i a i es we e smoo hly hyd ogena ed and u nished he co esponding p ima y amines in yields o up o 98% (Fig. 7, p oduc s 57–68). Phenylp opylamines a e ano he impo an class o pha maceu ically ele an amines. Fo example, he pa en compound (phenylp opylamine) is used in he syn hesis o ca boxypep idase B- ype enzyme inhibi o s, mus- ca inic ecep o an agonis s and po en ial an icance agen s. He e, i was p epa ed in 94% yield om he co esponding ni ile (Fig. 7, p oduc 69). Al hough 3-(a ylamino)p opaneni iles a e p epa ed in a s aigh o wa d manne om anilines and ac yloni ile, he hyd o- gena ion o such subs a es is di icul because e o-Michael addi- ions can occu . Howe e , his class o compounds was smoo hly hyd ogena ed unde ou condi ions o gi e he espec i e p ima y amines in good yields o up o 85% (Fig. 7, p oduc s 70–72). Finally, a selec ion o alipha ic ni iles was es ed. G a i yingly, Fe/Fe–O@ SiO2 also showed good- o-excellen ac i i y and selec i i y o hese demanding subs a es (Fig. 7, p oduc s 73–78). Pa icula ly in e - es ing is he selec i e educ ion o 5-hexeneni ile (Fig. 7, p oduc 78). No ably, hexame hylenediamine (79), he key eeds ock o he p oduc ion o nylon 66, was p epa ed in 85% yield by di ec hyd o- gena ion o adiponi ile. Simila ly, o he diamines we e ob ained in 90–95% yield (Fig. 7, p oduc s 80 and 81). Syn hesis o a y ni iles. Wi h a wo ldwide p oduc ion o a y amines o >800,000 ons y –1, he hyd ogena ion o a y ni iles cons i u es an impo an indus ial applica ion55. Fa y amines a e aluable oleochemicals mainly used o p oduce ab ic so ene s, lo a ion agen s, emulsi ie s, co osion inhibi o s and lub ica ing addi i es55. Un il oday, he indus ial hyd ogena ion o a y ni iles o amines has elied on well-es ablished Raney Ni o Co ca alys s as well as coppe ch omi e55. These ma e ials ha e conside able ox- ici y issues o biological sys ems. Hence, al e na i e Ru-, Pd- and 100 Fe g = 2.27 Da a 300 K/0 T Fi Fe(0) Fe(II) Fe(III) g = 2.015 g = 1.80 Si O 80 60 40 20 In ensi y (a.u.) In ensi y (a.u.) 0 2 100.0 ab cd 99.9 99.8 T ansmission (%) 99.7 –10 –5 0 Veloci y (mm s–1) 5 10 0 –2 –4 100 200 300 400 Magne ic ield (mT) 500 0 10 nm 5 10 Posi ion (nm) 15 20 25 Fig. 5 | Spec al da a o Fe/Fe–O@SiO2. a–d, HAADF-STEM image (a), dep h p o iles showing he in ensi y dis ibu ion o Fe, Si and O (b), Mössbaue spec um eco ded a 300 K (c) and EPR spec um (X-band 9.090 GHz) eco ded a 77 K (d). NaTuRe CaTalySiS | VOL 5 | JANUARY 2022 | 20–29 | www.na u e.com/na ca al 24 A icles NaTu e CaTalySIS Hyd ogena ion o benzoni iles Fe/Fe–O@SiO2 AI, 50 ba H2, 5–7 ba NH3 i-P OH, 120 °C, 24 h 3: 96%a (93%)a 4: 90% 9: 92% 15: 89% (90%) 16: 80%b 21: 95% 26: 91%b 31: 80%c 27: 94% 32: 80% 37: 89% 43: 85%b 47: 91%b 53: 90% 54: 85% 55: 94%b56: 92% 48: 89% (91%) 49: 90% 50: 91% (93%) 51: 93% 52: 65% 44: 95% 45: 60%d46: 90%e 38: 93% 39: 91% 40: 94% 41: 87% (84%) 42: 89% 33: 70%b34: 95% (93%) 35: 90% 36: 95% 28: 95% 29: 92%b30: 94% (92%) 22: 90%g24: 97% 25: 97% 17: 94% 18: 95% 19: 91% 20: 85% 10: 95% (95%) 11: 97% (96%) 12: 96% 13: 97% 14: 91% 6: 96%a7: 96% (95%) 8: 90% 5: 88%b (89%)b 23: 98%a Hyd ogena ion o he e ocyclic ni iles Fig. 6 | Subs a e scope. Hyd ogena ion o (he e o)a oma ic ni iles. Reac ion condi ions: 0.5 mmol ni ile, 40 mg Fe/Fe–O@SiO2 (8.5 mol% Fe), 3 mg Al oil (20 mol%), 5–7 ba NH3, 50 ba H2, 3 ml i-P OH, 120 °C, 24 h. Isola ed yields a e gi en. aYields we e de e mined by GC using n-hexadecane as s anda d. bWi h 50 mg Fe/Fe–O@SiO2. cWi h 50 mg Fe/Fe–O@SiO2 and 5 mg Al oil. dA 135 °C. eWi h 60 mg Fe/Fe–O@SiO2 and 5 mg Al oil. Wi h 50 mg Fe/Fe–O@SiO2 a 135 °C. gMe hyl 4-cyanobenzoa e was used as subs a e. T anses e i ica ion p oduc wi h i-P OH. Yields in pa en heses e e o he eac ion pe o med in he p esence o 20 mol% Al(i-OP )3. P oduc s we e isola ed as ee amines and con e ed o hei hyd ochlo ide sal s o NMR and high- esolu ion mass spec ome y (HRMS) analysis. NaTuRe CaTalySiS | VOL 5 | JANUARY 2022 | 20–29 | www.na u e.com/na ca al 25 A icles NaTu e CaTalySIS P -based ca alys s we e de eloped55. Un o una ely, none o hese sys ems is comme cially iable due o he high p ice o he p ecious me als. G a i yingly, ou ca alys is capable o hyd ogena ing a y ni iles in a highly selec i e manne . As a esul , se en di e en a y amines we e p epa ed in excellen yields o 95–97% (Fig. 8, p od- uc s 82–88). To u he p o e he syn he ic u ili y and p ac icabili y o ou Fe ca alys , we scaled up bo h he ca alys p epa a ion (up o 12 g; Supplemen a y Table 6) and he ni ile hyd ogena ion p o ocol (up o 20 g). Rega dless o he scale o p epa a ion (1–12 g), all he Fe ma e ials exhibi ed simila ac i i y and selec i i y (Supplemen a y Table 7). Nex , he ca aly ic hyd ogena ion eac ions o ou selec ed a oma ic and alipha ic ni iles we e pe o med using quan i ies o up o 20 g ni ile. Again, simila con e sions and yields we e ob ained o hose achie ed wi h small-scale eac ions using up o 100 mg ni ile (Supplemen a y Fig. 18). Finally, ca alys ecycling was in es iga ed a ull and hal con- e sions, which is an impo an aspec o any he e ogeneous ca a- lys . Indeed, he Fe/Fe–O@SiO2 ca alys could be eused up o he ou h un. A e ha , a dec ease in he p oduc yield was obse ed. Recycling es s pe o med a hal con e sion o 14 h showed a d op in ac i i y om he hi d un onwa d (Supplemen a y Fig. 19). Conclusions We ha e p esen ed he e he de elopmen o a he e ogeneous i on-based ca alys o he hyd ogena ion o ni iles. Key o success was he use o silica-suppo ed Fe nanopa icles co e ed wi h an ul a hin shell o amo phous i on(III) oxide (Fe/Fe–O@SiO2). These co e–shell nanopa icles we e p epa ed by simple imp egna ion o i on(II) ace- a e on comme cial silica and subsequen py olysis unde educ i e condi ions. The low cos and en i onmen ally iendly cha ac e o he ca alys , easy ecycling as well as upscaling o he syn he ic p ocess ep esen key ad an ages and make he ma e ial a ac i e o many applica ions. Impo an ly, he de eloped silica-suppo ed Fe/Fe–O co e–shell ma e ial exhibi ed high chemoselec i i y o he educ ion o unc ionalized and s uc u ally di e se a oma ic, he e ocyclic and alipha ic ni iles, including indus ially ele an a y ni iles, o p o- duce he co esponding p ima y amines in good- o-excellen yields. Aluminium alkoxide species gene a ed in si u om aluminium oil o aluminium iisop opoxide p o ed o be impo an o he co-ca aly ic ac i a ion o he ni ile subs a e. Me hods Gene al conside a ions. All ni iles we e ob ained comme cially om a ious chemical companies. Be o e using, he pu i y o all he ni iles was checked. I on(II) ace a e (99.99%, ca no. 517933-25G) was ob ained om Sigma Ald ich. Silica (Ae osil OX-50) was ob ained om E onik. Ca bon powde (VULCAN XC72R, wi h code XVC72R) was ob ained om Cabo Co po a ion. γ-Al2O3 and MgO we e ob ained om Sigma-Ald ich. Al oil was ob ained om Sigma-Ald ich (Mini Bin, HS23534A). Fo compa ison pu poses, Al oil used o ood co e ing was also pu chased om a local s o e (Kau land, ALUFOLIE; ICP). The pe cen age o aluminium in Al- oil was de e mined by induc i ely coupled plasma (ICP) and i was ound o be 99.97%. DMF was ob ained om Ac os Chemicals. Py olysis expe imen s we e ca ied ou in a Len on ube u nace. PXRD pa e ns we e measu ed a oom empe a u e wi h an Ae is di ac ome e (PANaly ical) in B agg–B en ano geome y equipped wi h Fe/Fe–O@SiO2 AI, 50 ba H2, 5–7 ba NH3 i-P OH, 120 °C, 24 h 57: 95% 58: 91% (93%) 59: 90% 62: 98% 67: 94% 72: 82% 73: 95%c 79: 85%d (89%)d80: 90%e (94%)e81: 95%e 74: 96%c75: 98%c 78: 65%c 77: 95%c 76: 97%a 68: 95% 69: 94% (92%) 70: 84% 71: 85% 63: 90% 64: 80%a 65: 89%b66: 91% 60: 90% 61: 91% Fig. 7 | Subs a e scope. Hyd ogena ion o alipha ic ni iles. Reac ion condi ions: 0.5 mmol ni ile, 40 mg Fe/Fe–O@SiO2 (8.5 mol% Fe), 3 mg Al oil (20 mol%), 5–7 ba NH3, 50 ba H2, 3 ml i-P OH, 120 °C, 24 h. Isola ed yields a e gi en. aWi h 50 mg Fe/Fe–O@SiO2. bA 135 °C. cYields we e de e mined by GC using n-hexadecane as s anda d. dWi h 80 mg Fe/Fe–O@SiO2 and 6 mg Al oil a 135 °C. eWi h 80 mg Fe/Fe–O@SiO2 and 6 mg Al oil a 120 °C. Yields in pa en heses e e o he eac ion pe o med in he p esence o 20 mol% Al(i-OP )3. P oduc s we e isola ed as ee amines and con e ed o hei hyd ochlo ide sal s o NMR and HRMS analysis. NaTuRe CaTalySiS | VOL 5 | JANUARY 2022 | 20–29 | www.na u e.com/na ca al 26 A icles NaTu e CaTalySIS an i on- il e ed Co Kα adia ion sou ce (40 kV, 15 mA, λ = 0.1789 nm) and PIXcell de ec o . Some samples we e measu ed employing an X’Pe PRO MPD di ac ome e (PANaly ical) in B agg–B en ano geome y equipped wi h a Co Kα adia ion sou ce (40 kV, 30 mA, λ = 0.1789 nm), p og ammable di e gence, di ac ed beam an i-sca e sli s and X’Cele a o de ec o . The angula ange o measu emen was 5–105° 2θ (Fe/Fe–O@SiO2 was measu ed in he ange 10–105° 2θ) wi h a s ep size o 0.022 and 0.033° o Ae is and X’Pe PRO MPD di ac ome e s, espec i ely. The c ys alline phases in he expe imen al PXRD pa e ns we e iden i ied using he X’Pe High Sco e Plus so wa e56 in conjunc ion wi h he PDF-4+57 and ICSD58 da abases. The comme cially a ailable silicon s anda d e e ence ma e ial SRM 640 was used o e alua e he line posi ions. Low- esolu ion TEM imaging o he ca alys mo phology was ca ied ou wi h a JEOL mic oscope equipped wi h a LaB6 emission gun, ope a ing a 160 kV. HRTEM images we e ob ained wi h a TITAN 60-300 HRTEM mic oscope equipped wi h an X-FEG- ype emission gun, ope a ing a 80 kV. This mic oscope was equipped wi h a Cs image co ec o and a HAADF-STEM ins umen . The poin esolu ion was 0.06 nm in TEM mode. Elemen al mapping was pe o med by STEM-EDS wi h an acquisi ion ime o 20 min. Fo he HRTEM analysis, he powde samples we e dispe sed in e hanol and ul asonica ed o 5 min. One d op o his solu ion was placed on a coppe g id suppo ing a holey ca bon ilm. The XPS su ace in es iga ion was pe o med on a PHI 5000 Ve saP obe II XPS sys em (Physical Elec onics) wi h a monoch oma ic Al Kα sou ce (15 kV, 50 W) and pho on ene gy o 1,486.7 eV. Dual beam cha ge compensa ion was used o all measu emen s. All spec a we e eco ded in a acuum o 1.3 × 10−7 Pa a 21 °C. A 200-µm-diame e spo was analysed o each sample. The su ey spec a we e measu ed wi h a pass ene gy o 187.850 eV and an elec on ol s ep o 0.8 eV, whe eas he high- esolu ion spec a we e eco ded wi h a pass ene gy o 23.500 eV and an elec on ol s ep o 0.2 eV. The spec a we e e alua ed wi h he Mul iPak so wa e (ULVAC-PHI). All binding ene gies a e e e enced o he C1s ca bon peak a 284.80 eV. The ansmission 57Fe Mössbaue spec a we e collec ed employing a Mössbaue MS96 spec ome e ope a ing in cons an accele a ion mode and equipped wi h a 40 mCi 57Co(Rh) sou ce. The Mössbaue spec a we e i ed wi h he MossWinn so wa e. The isome shi s a e e e enced o α-Fe a oom empe a u e. EPR spec a we e eco ded on a JEOL JES-X-320 spec ome e , ope a ing a he X-band equency (~9.14 GHz) a 77 K, and equipped wi h a JEOL ES 13060DVT5 a iable- empe a u e con ol appa a us. All ca aly ic expe imen s we e ca ied ou in 300 o 100 ml au ocla es (PARR Ins umen ). To a oid unspeci ic eac ions, all ca aly ic eac ions we e ca ied ou ei he in glass ials, which we e placed inside he au ocla e, o in au ocla es i ed wi h a glass/Te lon essel. GC and GC-mass spec ome y (GC–MS) we e pe o med on an Agilen Technologies 6890N ins umen . GC con e sions and yields we e de e mined by GC using lame ioniza ion de ec ion (FID) on an Agilen 6890N ch oma og aph equipped wi h Agilen HP-5MS 30m column (250 mm × 0.25 μm). The mass was de e mined by GC-MS using Agilen 6890N ch oma og aph equipped wi h Agilen HP-5MS 30m column (250 mm × 0.25 μm) and Agilen 5973N Mass Selec i e De ec o (MSD). 1H and 13C NMR spec a we e eco ded on B uke ARX 300 and ARX 400 spec ome e s using [D6]DMSO and CDCl3 sol en s. P epa a ion o Fe/Fe–O@SiO2 on he 1.5 g scale. A magne ic s i ing ba and 280.33 mg Fe(OAc)2 we e ans e ed o a 50- ml ound-bo omed lask and 30 ml DMF was added. The eac ion mix u e was s i ed a 50 °C o dissol e he i on ace a e. To his solu ion, 1.2 g SiO2 (Ae osil OX 50) was added, ollowed by 10 ml DMF. Nex , a e lux condense was i ed o he ound-bo omed lask con aining he eac ion mix u e, which was hen placed in an aluminium block p ehea ed a 150 °C and s i ed o 4 h. Nex , he e lux condense was emo ed and he ound-bo omed lask con aining he eac ion p oduc s was allowed o s and wi hou s i ing o closing o 20 h a 150 °C o he slow e apo a ion o DMF. A e e apo a ion o he sol en and ensu ing comple e d ying, he solid ma e ial was cooled o oom empe a u e and g ound o a ine powde . This powde was py olysed a a de ined empe a u e (400, 600, 800 o 1,000 °C) o 4 h in a ubula u nace unde he low o 20% H2/N2 ( amp: 5 °C min–1, o al low: 3 l h–1) and hen cooled o oom empe a u e. Elemen al analysis o Fe/Fe–O@SiO2 by ICP and CHN analysis e ealed he ollowing (w %) dis ibu ion: Fe = 6.09%; Si = 37.73%; C = 0.11%; H = 0.41%. The B unaue –Emme –Telle su ace a ea was measu ed o be 46.04 m2 g–1. The same p ocedu e was employed o he p epa a ion o Fe(OAc)2-C-800, Fe(OAc)2-γ-Al2O3-800 and Fe(OAc)2-MgO-800. P epa a ion o Fe/Fe–O@SiO2 on 6 and 12 g ba ches. The same p ocedu e was used o he p epa a ion o Fe/Fe–O@SiO2 (Fe(OAc)2-SiO2-800) on he 6 and 12 g scale wi h a sligh modi ica ion o he py olysis p ocedu e, as desc ibed in Supplemen a y Table 6. Gene al p ocedu e o he hyd ogena ion o ni iles. A magne ic s i ing ba and 0.5 mmol o he co esponding ni ile we e ans e ed o a 7-ml glass ial and hen 3 ml i-P OH was added. Nex , 40 mg Fe/Fe–O@SiO2 (8.5 mol% Fe) and 3 mg Al oil ( he Al oil was cu in o small pieces and used in he eac ions) o 20.42 mg Al(i-OP )3 (20 mol%) we e added and he ial was i ed wi h a sep um, cap and needle. Then, he eac ion ials we e placed in a 300-ml au ocla e (eigh ials con aining di e en subs a es a a ime). The au ocla e was closed, lushed wice wi h 20 ba hyd ogen and hen p essu ized wi h 5–7 ba ammonia gas and 50 ba hyd ogen. The au ocla e was placed in an aluminium block p ehea ed a 133 °C and he eac ions we e allowed o p oceed o he equi ed ime unde s i ing. Fa s and oils 82: 97% (97%) 85: 96%b86: 95%b (95%) 87: 97%b 88: 95%b (94%)b 83: 97% 84: 97%a Fa y amines Fa y ni iles P e iously used ca alys s Raney Ni o Co, Cu ch omi e, Ru, Pd, P This Fe ca alys (Oc ylamine) (My is ylamine) (S ea ylamine) (Nonadecanamine) (Hep adecylamine) (Decylamine) (Lau ylamine) Fe/Fe–O@SiO2 NH3, H2 120 °C, 24 h Fig. 8 | Subs a e scope. Syn hesis o a y amines. Reac ion condi ions: 0.5 mmol ni ile, 40 mg Fe/Fe–O@SiO2 (8.5 mol% Fe), 3 mg Al oil (20 mol%), 5–7 ba NH3, 50 ba H2, 3 ml i-P OH, 120 °C, 24 h. Isola ed yields a e gi en. aA 135 °C. bWi h 50 mg Fe/Fe–O@SiO2. Yields in pa en heses e e o he eac ion pe o med in he p esence o 20 mol% Al(i-OP )3. P oduc s we e isola ed as ee amines and con e ed o hei hyd ochlo ide sal s o NMR and HRMS analysis. NaTuRe CaTalySiS | VOL 5 | JANUARY 2022 | 20–29 | www.na u e.com/na ca al 27 A icles NaTu e CaTalySIS Du ing he eac ions, he inside empe a u e o he au ocla e was measu ed o be 120 °C, and his empe a u e was conside ed o be he eac ion empe a u e. A e comple ion o he hyd ogena ion eac ions, he au ocla e was cooled o oom empe a u e. The emaining ammonia and hyd ogen we e discha ged and he ials con aining he eac ion p oduc s we e emo ed om he au ocla e. The solid ca alys was il e ed and washed ho oughly wi h e hyl ace a e. The eac ion p oduc s we e analysed by GC–MS. The co esponding p ima y amines we e pu i ied by column ch oma og aphy (silica, me hanol–dichlo ome hane). The amines we e con e ed o hei espec i e hyd ochlo ide sal and cha ac e ized by GC–MS and NMR analysis. To con e he amines o he hyd ochlo ide sal s, 1–2 ml me hanolic HCl (0.5 M HCl in me hanol) was added o he e hyl ace a e solu ion o he espec i e amine and he mix u e s i ed a oom empe a u e o 4–5 h. Then, he sol en was emo ed and he esul ing hyd ochlo ide sal was d ied unde high acuum. Fo selec ed amines, he yields we e de e mined by GC using he ollowing p ocedu e. A e comple ing he eac ion, n-hexadecane (100 µl) was added as s anda d o he eac ion ials and he eac ion p oduc s we e dilu ed wi h e hyl ace a e ollowed by il a ion using a plug o silica and hen analysed by GC. G am-scale eac ions. A magne ic s i ing ba and he co esponding ni ile we e ans e ed o a glass- i ed 300-ml Pa au ocla e and 15–50 ml i-P OH was added. Nex , he equi ed amoun o ca alys (Fe/Fe–O@SiO2, 8.5–10 mol%) and Al oil (20 mol%; he Al oil was cu in o small pieces and used in he eac ions) we e added. Then, he au ocla e was closed, lushed wice wi h 20 ba hyd ogen and hen p essu ized wi h 5–7 ba NH3 ollowed by 50 ba hyd ogen. The au ocla e was placed in an aluminium block p ehea ed a 133–147 °C (placed 30 min be o e coun ing he eac ion ime o achie e he eac ion empe a u e) and he eac ions we e s i ed o 24 h. Du ing he eac ions, he inside empe a u e o he au ocla e was measu ed o be 120–135 °C. A e comple ion o he eac ions, he au ocla e was cooled o oom empe a u e. The emaining ammonia and hyd ogen we e discha ged, and he eac ion p oduc s we e emo ed om he au ocla e. The solid ca alys was il e ed and washed ho oughly wi h me hanol and e hyl ace a e. The eac ion p oduc s we e analysed by GC–MS and he co esponding p oduc s we e pu i ied by column ch oma og aphy (silica, dichlo ome hane–me hanol) and cha ac e ized by NMR and GC–MS analysis. Ca alys ecycling. A magne ic s i ing ba and 10 mmol benzoni ile we e ans e ed o a 100-ml au ocla e and hen 20 ml i-P OH was added. Nex , 900 mg ca alys (Fe/Fe–O@SiO2) and 408.50 mg Al(i-OP )3 we e added. The au ocla e was closed, lushed wi h 20 ba hyd ogen and hen p essu ized wi h 5–7 ba NH3 and 50 ba H2. The au ocla e was placed in a p ehea ed aluminium block a 130 °C and he eac ions we e s i ed o he equi ed ime. Du ing he eac ions, he inside empe a u e o he au ocla e was measu ed o be 120 °C. A e comple ion o he eac ions, he au ocla e was cooled o oom empe a u e. The emaining ammonia and hyd ogen we e hen discha ged, and he eac ion p oduc s we e emo ed om he au ocla e. Nex , 250 µl n-hexadecane was added as s anda d o he eac ion p oduc s. The ca alys was sepa a ed by il a ion and he il a e con aining he eac ion p oduc s was subjec ed o GC analysis o de e mine he yield o benzylamine. The sepa a ed ca alys was washed wi h e hyl ace a e, d ied unde acuum and used wi hou u he pu i ica ion o eac i a ion o he nex un. Da a a ailabili y All da a a e a ailable om he au ho s upon easonable eques . Recei ed: 31 Ma ch 2021; Accep ed: 10 No embe 2021; Published online: 30 Decembe 2021 Re e ences 1. Belle , M. & Bolm, C. T ansi ion Me als o O ganic Syn hesis (Wiley-VCH, 2008). 2. Negishi, E.-I. Magical powe o ansi ion me als: pas , p esen , and u u e (Nobel lec u e). Angew. Chem. In . Ed. 50, 6738–6764 (2011). 3. Hagen, J.Indus ial Ca alysis: A P ac ical App oach (Wiley‐VCH, 2006). 4. Ca low, C. R., Da idson, M., Ha dac e, C. & Hu chings, G. J. Ca alysis making he wo ld a be e place. Philos. T ans. R. Soc. A 374, 20150089 (2016). 5. Busacca, C. A., Fand ick, D. R., Song, J. J. & Senanayake, C. H. The g owing impac o ca alysis in he pha maceu ical indus y. Ad . Syn h. Ca al. 353, 1825–1864 (2011). 6. Rylande , P. N.Ca aly ic Hyd ogena ion in O ganic Syn heses (Academic P ess, 1979). 7. Alonso, D. A. e al. in Science o Syn hesis: Wa e in O ganic Syn hesis (ed. Kobayashi, S.) 95–119 (Thieme, 2012); h ps://doi.o g/10.1055/ sos-SD-206-00075 8. Oge , C., Balas, L., Du and, T. & Galano, J.-M. A e alkyne educ ions chemo-, egio-, and s e eoselec i e enough o p o ide pu e (Z)-ole ins in poly unc ionalized bioac i e molecules? Chem. Re . 113, 1313–1350 (2013). 9. Massa o, L., Zheng, J., Ma ga i a, C. & Ande sson, P. G. Enan iocon e gen and enan iodi e gen ca aly ic hyd ogena ion o isome ic ole ins. Chem. Soc. Re . 49, 2504–2522 (2020). 10. Chi ik, P. J. I on- and cobal -ca alyzed alkene hyd ogena ion: ca alysis wi h bo h edox-ac i e and s ong ield ligands. Acc. Chem. Res. 48, 1687–1695 (2015). 11. Magano, J. & Dune z, J. R. La ge-scale ca bonyl educ ions in he pha maceu ical indus y. O g. P ocess Res. De . 16, 1156–1184 (2012). 12. Zhong, R., Wie, Z., Zhang, W., Liu, S. & Liu, Q. A p ac ical and s e eoselec i e in si u NHC-cobal ca aly ic sys em o hyd ogena ion o ke ones and aldehydes. Chem 5, 1552–1566 (2019). 13. Fo men i, D., Fe e i, F., Scha nagl, F. K. & Belle , M. Reduc ion o ni o compounds using 3d-non-noble me al ca alys s. Chem. Re . 119, 2611–2680 (2019). 14. Jagadeesh, R. V. e al. Nanoscale Fe2O3-based ca alys s o selec i e hyd ogena ion o ni oa enes o anilines. Science 342, 1073–1076 (2013). 15. Wiesen eld , M. P., Nai oukh, Z., Dal on, T. & Glo ius, F. Selec i e a ene hyd ogena ion o di ec access o sa u a ed ca bo- and he e ocycles. Angew. Chem. In . Ed. 58, 10460–10476 (2019). 16. Mu ugesan, K. e al. Cobal -nanopa icles ca alyzed e icien and selec i e hyd ogena ion o a oma ic hyd oca bons. ACS Ca al. 9, 8581–8591 (2019). 17. Sahoo, B. e al. A obus i on ca alys o he selec i e hyd ogena ion o subs i u ed (iso)quinolones. Chem. Sci. 9, 8134–8141 (2018). 18. Law ence, S. A. Amines: Syn hesis, P ope ies and Applica ions (Camb idge Uni . P ess, 2004). 19. Ricci, A. Amino G oup Chemis y: F om Syn hesis o he Li e Sciences (Wiley-VCH, 2008). 20. Qu eshi, M. H. Top 200 Pha maceu icals by Re ails Sales in 2020 (Uni e si y o A izona, 2020); h ps://nja da son.lab.a izona.edu/si es/nja da son.lab. a izona.edu/ iles/Top%20200%20Pha maceu icals%20By%20Re ail%20 Sales%202020V3.pd 21. Mu ugesan, K. e al. Ca aly ic educ i e amina ions using molecula hyd ogen o syn hesis o di e en kinds o amines. Chem. Soc. Re . 49, 6273–6328 (2020). 22. Hahn, G., Kunnas, P., de Jonge, N. & Kempe, R. Gene al syn hesis o p ima y amines ia educ i e amina ion employing a eusable nickel ca alys . Na . Ca al. 2, 71–77 (2019). 23. Saba ie , P. & Sende ens, J. B. Applica ion aux ni iles de la me hode d’hyd ogena ion di ec e pa ca alyse: syn hese d’amines p imai es, secondai es e e iai es. C. R. Hebd. Séances Acad. Sci. 140, 482–484 (1905). 24. Paal, C. & Ge um, J. Übe ka aly ische Wi kungen kolloidale Me alle de Pla ing uppe. VI. Reduk ionska alysen mi kolloidalem Palladium. Be . D sch. Chem. Ges. 42, 1553–1560 (1909). 25. B aun, V. J., Blessing, G. & Zobel, F. Ka aly ische hyd ie ungen un e D uck bei Gegenwa on nickelsalzen. VI.: ni ile. Be . D sch. Chem. Ges. A 56, 1988–2001 (1923). 26. Raney, M. Me hod o p epa ing ca aly ic ma e ial. US pa en 1563587A (1925). 27. Ca o he s, W. H. & Jones, G. A. The p epa a ion o some p ima y amines by he ca aly ic educ ion o ni iles. J. Am. Chem. Soc. 47, 3051–3057 (1925). 28. Alle , B. V. Raney cobal hyd ogena ion ca alys s. I. The p epa a ion o he ca alys . J. Appl. Chem. 7, 130–134 (2007). 29. Ad kins, H. Reac ions o Hyd ogen wi h O ganic Compounds O e Coppe -Ch omium Oxide and Nickel Ca alys s 53 (Uni . Wisconsin P ess, 1937). 30. F ei elde , M. A low p essu e p ocess o he educ ion o ni iles. Use o hodium ca alys . J. Am. Chem. Soc. 82, 2386–2389 (1960). 31. F eidlin, L. K. & Sladko a, T. A. Ca aly ic educ ion o dini iles. Russ. Chem. Re . 33, 319–330 (1964). 32. Ba ne , C. Hyd ogena ion o alipha ic ni iles o e ansi ion me al bo ides. Ind. Eng. Chem. P od. Res. De . 8, 145–149 (1969). 33. de Belle on, C. & Fouilloux, P. Homogeneous and he e ogeneous hyd ogena ion o ni iles in a liquid phase: chemical, mechanis ic, and ca aly ic aspec s. Ca al. Re . 36, 459–506 (1994). 34. López-De Jesús, Y. M., Johnson, C. E., Monnie , J. R. & Williams, C. T. Selec i e hyd ogena ion o benzoni ile by alumina-suppo ed I –Pd ca alys s. Top. Ca al. 53, 1132–1137 (2010). 35. Lé ay, K. & Hegedűs, L. Recen achie emen s in he hyd ogena ion o ni iles ca alyzed by ansi ional me als. Cu . O g. Chem. 23, 1881–1900 (2019). 36. Yoshimu a, M. e al. Selec i e syn hesis o p ima y amines om ni iles unde hyd ogena ion condi ions. Ad . Syn h. Ca al. 360, 1726–1732 (2018). 37. Liu, Y. e al. Mild palladium-ca alysed highly e icien hyd ogena ion o C≡N, C–NO2, and C=O bonds using H2 o 1 a m in H2O. G een Chem. 21, 830–838 (2019). 38. Wang, H. e al. Quasi Pd1Ni single-a om su ace alloy ca alys enables hyd ogena ion o ni iles o seconda y amines. Na . Commun. 10, 4998 (2019). 39. Ryabchuk, P. e al. In e me allic nickel silicide nanoca alys —a non-noble me al–based gene al hyd ogena ion ca alys . Sci. Ad . 4, eaa 0761 (2018). NaTuRe CaTalySiS | VOL 5 | JANUARY 2022 | 20–29 | www.na u e.com/na ca al 28