Fe Incorporation Regulates The Distribution Of Acid Sites Of MOR Zeolite And Its Catalytic Performance On The Carbonylation Of Dimethyl Ether

Ethanol is an important chemical intermediate and a kind of green energy,which is one of the most promising alternatives to fossil fuels.The carbonylation of dimethyl ether（DME）to methyl acetate（MA）followed by hydrogenation is a promising synthesis route for converting syngas into ethanol duo to its superior atom economy and mild reaction condition in industry.HMOR zeolite exhibits unique activity and high selectivity because of its porous structure and acid property.However,the highly active HMOR generally suffers from a fast deactivation.Tailoring the distribution of Br（?）nsted acid sites in 8-MR(B_8-MR)and 12-MR(B_12-MR)is demonstrated as an efficient method to significantly improve the catalytic stability and activity.Metal incorporation is a simple and efficient way to regulate the distribution of acid sites.Focusing on the Fe-doped MOR,the present thesis investigates the effects of introducing Fe atoms into the framework of MOR zeolite by different ways on the acid sites distribution and carbonylation performance of DME.Designing a series of Fe-doped MOR zeolites using oxalic acid as the complexing reagent by one-pot hydrothermal method.Combining many characterization methods,it is found that the Fe preferentially locates at the T3 position of 8-MR and the acid distribution of HMOR can be selectively regulated.The number of B_8-MR shows a steep gradient decline,while the number of the B_12-MR is well maintained.In the DME carbonylation test,although the decrease of B_8-MR reduces the conversion of DME,it significantly improves the stability of catalysts and suppress the formation of heavy coke.For the 0.75Fe-HM,the conversion of DME slightly decrease and the selectivity of MA still maintains over 90%after 35 h.A series of the Fe-doped MOR using different Fe sources such as Fe₂（SO₄）₃,Fe（NO₃）₃ and FeCl₃ via one-pot hydrothermal synthesis method were prepared.It was found that different Fe sources have different effects on regulating the distribution of acid sites.When using Fe₂（SO₄）₃ and Fe（NO₃）₃ as the Fe sources,the catalytic activity exhibited a volcanic trend with the increasing of Fe content.0.2SFe-HM with the relatively abundant B_8-MR showed high catalytic performance that the conversion of DME reached 99%and the maximum space-time yield of MA was 0.35 g/（g·h）.Compared to the parent HM-96,the DME conversion and the maximum space-time yield of MA increases by nearly 40.52%and 45.8%,respectively.However,the catalytic activity of MOR was not promoted when FeCl₃ was used as the Fe source.Herein,Fe-doped MOR zeolites were prepared by two different doping methods.The regulation mechanism of the introduction of Fe into the framework on the acid distribution of MOR zeolite was explored,and the effect of acid distribution on the performance of DME carbonylation was studied as well.The study provides simple and feasible methods to improve the catalytic performance of DME carbonylation reaction over MOR zeolite.