Rh-based Catalyst From Perovskite-type Oxides For Higher Alcohols Synthesis From Syngas

Higher alcohol is an excellent additive to gasoline.not only can it increase the octane level of gasoline,but also reduce the emissions of SO₂ and other polluting gases from traditional fossil fuel combustion.This has caused widespread concern in recent years.Synthesis of mixed alcohols are a viable technological route,which was proposed in last century and has always been hot spots at home and abroad.The research of Rh-based catalysts for higher alcohol synthesis has a long history.Researches on all aspects of the catalyst has been done.But the system remains many problems,such as the lower activity of the catalyst,low effective utilization and many other issues,these issues limits its application on a large scale.Therefore,exploring innovative approaches and used for the catalyst aiming at bringing some new breakthrough is of great significance.Preparation of rhodium-based catalyst mainly uses the traditional impregnation method,the method is easy to make the random distribution of active component and additives,then producing large amounts of by-products.In this article,Rh and corresponding additives were deposited in perovskite-type molecules firstly.further reduction,Rh and active components were loaded closely.Perovskite composite oxides varied,all whose A and B ions can be replaced.By partly replacing B elements,common additives can enter the perovskite structure and coexist in a molecule with Rh.After hydrogen reduction,rhodium and corresponding additives are more close to each other,so as to enhance the interaction.Firstly,we use citric acid dipping preparing supported LaRh_0.33Mn_0.67O₃ catalysts.Compared with common rhodium-based catalyst,perovskite catalyst precursors have a certain improvement in activity,however alcohol selective changes not particularly significant.It can be seen that Rh and Mn while placed in perovskite-type complex oxide catalysts for further reduction can improve performance.Perovskite complex oxide as catalyst precursors further restoring more Rh-MnOx species is a major cause of catalyst activity.Then YRhO₃/ZrO₂,YRh_0.5Fe_0.5O₃/ZrO₂ loading catalysts were prepared by improved citrate complex-impregnation method,for comparison at the same time Rh/ZrO₂ and Rh-Fe/ZrO₂ catalysts were also prepared by impregnation method.Inquiry focuses on the enhancing effect of perovskite precursor on Rh-Fe bimetallic catalyst.Compared with traditional Rh-Fe bimetallic catalyst,YRh_0.5Fe_0.5O₃/ZrO₂ catalyst showed higher selectivity of total alcohol.Especially ethanol accounted for close to 75% proportion in the total alcohol.The formation of a large number of Rh-Fe metal alloys is the main reason.Perovskite precursor components rhodium and iron oxide additives into the same macromolecule,after restoring almost all of rhodium,iron were in the form of Rh-Fe alloys.These bi-metallic alloy greatly promoted the migration of CO and hence exhibiting better catalytic performance.