Preparation Of Novel Hybrid Nanostructured Co And Ni Catalysts And Study On Selective Hydrogenation Of Nitrobenzene

Aniline is widely used in chemical raw materials and fine chemicals.It is mainly used in diphenylmethane diisocyanate（MDI）products,and it is also the most demanded high-value intermediate at present.The liquid-phase hydrogenation of nitrobenzene to prepare aniline is currently the most widely used,safest and most environmentally friendly production process.This process mostly uses precious metal catalysts（such as Pd,Pt,Ru,Au,etc.）.However,due to the high cost,limited durability and easy deactivation of precious metals,non-precious metal catalysts have become the focus of attention,especially Co,Ni Catalysts.This type of catalyst is loved by many domestic and foreign scholars due to its low price and stable performance.However,the non-noble metal catalysts currently reported have low activity and complicated preparation conditions,and the reaction conditions and results still cannot achieve satisfactory results,which hinders the large-scale development of such catalysts.Therefore,it is particularly important to develop a low-cost,mild reaction condition,good catalytic activity,and environmentally friendly catalyst to catalyze the selective hydrogenation of nitrobenzene to prepare aniline.This paper proposes a novel hybrid nanostructured Co and Ni catalyst strategy:the combination of non-noble metals and semiconductor films can achieve the synergistic catalytic effect of 1+1>>2.According to this novel strategy,a high Active hybrid nanostructured Co and Ni catalysts.Through the combination of precipitation method and vapor phase reduction method,according to the principle of spontaneous monolayer dispersion,the semiconductor oxide Zr O₂is spread on the molecular sieve carrier in a single layer or multiple layers,and Co and Ni metal particles are embedded/loaded on the semiconductor film layer to prepare A new type of hybrid nano-structured Co/@-Zr O₂/SBA-15,Ni/@-Zr O₂/SBA-15,Ni/@-Zr O₂/MCM-22catalysts have been systematically investigated to catalyze nitro groups.The performance of benzene hydrogenation,the conclusions are as follows:1.Co/@-Zr O₂/SBA-15,Ni/@-Zr O₂/SBA-15,Ni/@-Zr O₂/MCM-22 catalysts were prepared by precipitation method-gas phase reduction method and passed XRD,TEM,XPS,BET Other characterizations confirmed that this type of catalyst has a large specific surface area,and the active component has a small particle size and is uniformly dispersed;Ni or Co nanoparticles are embedded or supported on the semiconductor Zr O₂film with a special structure morphology.2.Nitrobenzene hydrogenation reduction reaction:Co/@-Zr O₂/SBA-15 at120℃,1MPa,reaction for 4h.Ni/@-Zr O₂/SBA-15 at 120℃,1MPa,reaction for30min.Ni/@-Zr O₂/MCM-22 When the conditions are 120℃,1MPa,reaction for30min.the three catalysts have the best catalytic effect on nitrobenzene,100%nitrobenzene conversion rate and 99.99%aniline selectivity.3.There are strong interactions between Co,Ni and the semiconductor Zr O₂film carrier,electronic effects and interface effects,and the p-nitrobenzene nitro group has a strong preferential adsorption and specificity,so as to achieve the p-nitro group.Benzene selective hydrogenation has the characteristics of high efficiency,high selection and high stability,and its catalytic performance is excellent.