Research Of Gas Adsorption By Rh Nanoparticles And Catalytic Methanation Of CO₂

As an important catalytic material,Rh nanoparticles are widely used in automobile exhaust purification,petrochemical,environmental protection,pharmaceutical and chemical industries,among which hydroformylation of olefins is one of the largest industrial applications of soluble phosphon-rhodium complex catalysts.In the process of hydroformylation of high carbon alkenes,the homogeneous catalyst was inactivated due to its high boiling point and thermal stability.At the same time,it is difficult to separate the catalyst and recover the precious metal rhodium.However,understanding and accurately predicting their structural evolution remains a challenging and demanding task.Rh has been shown to reduce NOX more effectively than Pt and Pd.However,Rh is much rarer and more expensive than other metals.Therefore,to further understand and develop a more efficient and economical next generation catalyst,Rh catalyst needs to be optimized.The catalytic properties of Rh nanoparticles were studied in this paper.In the first part of this paper,we systematically studied the structural evolution of Rh NPs under the adsorption conditions of different gases（H₂,O₂,N₂,CO,NO,CO₂,NO₂,H₂O）by using the newly developed multi-scale structure reconstruction model.The results showed that O₂,NO,CO,NO₂and other adsorbent gases significantly changed the shape of Rh NP at pressures as low as 1pa.Gases with weak adsorption capacity,such as H₂,N₂,CO₂,H₂O vapor,etc.,have less influence under low pressure.Interestingly,under certain environmental conditions,weakly adsorptive gases such as N₂may cause unexpected changes in the shape of Rh NP.This study provides guidance for the practical study of Rh-based catalytic reactions.In the second part of this paper,we used Ti O₂-Rh（Ti O₂rutile structure as the base to adsorb one atom of Rh）and Ti O₂-Rh₂（Ti O₂rutile structure as the base to adsorb two Rh atoms）as the catalyst.The catalytic selectivity of reduction of CO₂by hydrogen was studied theoretically.This work shows that small clusters of isolated atoms on the same carrier and small clusters of nanoparticles on the same metal can exhibit unique and different catalytic selectivity in competing parallel reaction paths.