Study On Modification Of Hydrogen Mordenite And Its Dimethyl Ether Carbonylation And Methyl Acetate Hydrogenation Performance

Ethanol is considered to be a renewable energy source that replaces or improves conventional fossil fuels.The process route of producing ethanol from synthesis gas,especially the production of dimethyl ether（DME）from synthesis gas,followed by DME carbonylation and methyl acetate（MA）hydrogenation to produce ethanol,can achieve high value-added utilization of coal resources,and It can solve the problem of overcapacity in my country such as dimethyl ether and methanol.Among various carbonylation catalysts,hydrogen-type mordenite（HMOR）has good catalytic performance for the carbonylation of DME to MA and can avoid the use of noble metals and corrosive iodides.But the main challenge it faces is that the Bronsted acid（B acid）of the twelve-membered ring（12-MR）of HMOR is easy to cause the carbon deposition reaction,which leads to the rapid deactivation of the catalyst.Increasing the number and strength of B acid in the eight-membered ring（8-MR）and the junction of the 12-MR and 8-MR side pockets,and selectively shielding the B acid sites in the 12-MR channel is to increase the HMOR carbonylation reaction activity and The key to stability.In this paper,an ion exchange method was used to modify HMOR with the hydrochloride of a nitrogen-containing heterocyclic compound,which significantly improved the carbonylation activity and stability of the modified HMOR catalyst.Using characterization techniques such as NH₃-TPD,Py-IR,UV-vis,etc.,the influence of the type,preparation process and reaction process conditions of the hydrochloride of nitrogen heterocyclic compound on the catalytic performance of the catalyst was discussed,and the relationship between the structure and performance of the catalyst was explained.The main research results obtained are as follows:Using pyrazole,2-methylimidazole,pyridine,imidazole and other nitrogen heterocyclic hydrochloride to modify HMOR not only improves its carbonylation activity,but also significantly improves the stability of its carbonylation reaction.Studies have shown that the lower the p H of the nitrogen-containing heterocyclic hydrochloride,the higher the activity of the modified HMOR catalyst,but the stability shows a downward trend;the stronger the basicity and the higher the boiling point of the nitrogen-containing heterocyclic salt,the more stable the modified HMOR.HMOR modified by pyrazole hydrochloride has good carbonylation activity and stability;after modification by pyrazole hydrochloride,the amount of B acid in the aluminotetrahedron at the junction of the 12-MR and 8-MR side pockets of HMOR The increase in strength and strength improves the activity of the catalyst;the non-framework Al species of HMOR are effectively removed,and the B acid in the 12-MR channel is replaced by Pyrazole ions（HPya⁺）,which inhibits the occurrence of side reactions of carbon deposition and improves the carbonylation reaction of the modified HMOR With the increase of the concentration of pyrazole hydrochloride and ion exchange temperature,the conversion rate of DME shows an increasing trend.The suitable concentration of pyrazole hydrochloride is 0.85～1.3 mol/L,which is suitable for ion exchange.The temperature is 80～95℃.The suitable operating process conditions for pyrazole hydrochloride modified HMOR in the carbonylation reaction are:pressure 1.5～2.0 MPa,temperature 200～220℃,space velocity 3000～4500 m L/（g·h）.After Na-MOR was modified with pyrazole hydrochloride,the Na⁺in the 8-MR and 12-MR channels were replaced by exchange,and it showed good DME carbonylation activity and stability.The HMOR modified by pyrazole hydrochloride and the copper-based catalyst can be connected in series to construct a two-catalyst bed structure carbonylation-hydrogenation integrated reaction system,which shows good performance of DME carbonylation and MA hydrogenation.DME The conversion rate is 75～97%,and the ethanol selectivity is 25～30 %.