Study On Catalytic Hydrogenation Of Methyl Acetate To Ethanol

Ethanol is an important commodity chemical,it is widely used in energy,chemical,food,medicine and other fields.Because ethanol can be used as a kind of clean energy,not only can replace the traditional tetraethyl lead as gasoline antiknock agent,but also can be further processing for fuel ethanol,reduce the pollution from the burning of gasoline.At present,the mainly process in the production for ethanol are food fermentation and ethylene hydration.The food fermentation have many obvious problems that the primary materials compete with people for food and contest with food for the fields,and the production cost is higher,need the state financial subsidies to survive,so need to find a non-food based method for producing ethanol.And ethylene hydrate synthetic raw material is oil,it is not correspond with our country's basic national conditions that“rich coal less oil and natural gas”.So it is very necessary to look for a kind of non-food and non-oil based method for producing ethanol.Since the 1980s,carbonylation of methanol to acetic acid technology has continued to mature,make serious overcapacity acetic acid industry in our country;our country has become the largest producer of acetic acid.In downstream industries,acetate with acetic acid as raw material to produce ethanol can be a large amount of consumption of acetic acid,and produce clean fuel ethanol.It has found new methods for producing ethanol.Direct hydrogenation of acetic acid to produce ethanol has the disadvantages of high requirements for equipment,and acetic acid ester that acetic acid by the esterification hydrogenation has low requirements for equipment materials and uses non-noble metal catalysts,thus indirectly acetate ethanol hydrogenation system advantage is significant,the core of the process lies in the development of acetic ester hydrogenation catalyst.This paper mainly studied the preparation of hydrogenation catalyst and optimum technological conditions of catalytic hydrogenation of methyl acetate reactions system of ethanol.Chose proper precipitant and way of feeding,calcination temperature,copper content,additives,Cu:Zn:Al quality ratios,studied the effect of preparation conditions on the catalytic performance of catalysts.Based on the selection of catalyst,studied the process conditions affect the performance of catalyst reaction,examined the stability of catalyst,and analyzed the causes of catalyst deactivation.This paper mainly divided into two parts:The first part is the preparation of high efficient catalyst that hydrogenation of methyl acetate to ethanol.Investigation and research on a series of catalyst,the catalyst preparation conditions were determined.Precipitant is Na₂CO₃ and way of feeding is addition,calcination temperature is 450°C,the copper content is 40%,choose zinc as additives,Cu:Zn:Al quality ratios is 5:2:1.According to the above conditions,CuO-ZnO/Al₂O₃ catalyst was prepared.Catalyst precursor of architecture was most neat,CuO particles get smaller after roasting and scattered the most uniform,with more and dispersion of active component,showed the optimal effect of hydrogenation.The conversion rate of methyl acetate was 97.62%,the selectivity of ethanol was 97.57%.At the same time,the catalysts were characterized by N₂adsorption-desorption?BET?,X-ray diffraction?XRD?,temperature-programmed reduction?H₂-TPR?,transmission electron microscope?TEM?,scanning electron microscope?SEM?analysis of the physical and chemical properties of catalysts,to explore the relationship between the catalyst structure and catalytic activity.The second part is the optimization of process conditions that catalytic hydrogenation of methyl acetate to ethanol.This experiment mainly examines the reaction temperature,reaction pressure and hydrogen ester molar ratio and the LHSV of methyl acetate four factors.The results showed that temperature is 230°C,pressure is 3.0 MPa,LHSV of methyl acetate is 1.0h^-1,hydrogen ester molar ratio is 10:1,catalytic hydrogenation of methyl acetate to ethanol achieved the optimal effect.Under the reaction conditions,the conversion of methyl acetate is98.63%,the selectivity of ethanol is 98.13%.Investigates the performance of the 3 months of catalyst conversion rate reduced from 98.63%to 98.63%of methyl acetate,ethanol selectivity decreased from 98.13%to 98.13%,and the catalyst has high activity and stability of catalyst deactivation,continue to run a certain time by TEM analysis,can determine the catalyst deactivation reason is that the accumulation of copper particles grew up.