Preparation And Catalytic Performance Of Y-type Zeolite In-suit Encapsulated Tungstophosphoric Acid Catalyst

With the increase in global energy demand,biodiesel has become one of the alternative energy sources for petroleum fuels due to its green and renewable characteristics.Transesterification is the most widely used and reliable technology in biodiesel production.In the production of biodiesel,catalysts play an important role in the quality and yield of biodiesel.In particular,the encapsulated solid acid catalyst has good activity and stability,and has important research value in biodiesel production.In this paper,Y zeolite was used to prepare the in-suit encapsulated catalyst.The esterification reaction of oleic acid and methanol was used to investigate the catalytic performance of the catalyst.The fatty acids obtained from the hydrolysis of kitchen waste oil were used to prepare biodiesel.Various characterization methods were used to analyze and study the elemental composition,crystal structure,and functional groups of the catalyst.Comprehensive research and analysis of catalyst preparation methods and their applications in oleate and biodiesel production.Provide further guidance value for the preparation of encapsulated catalysts and the production of biodiesel.Through experiments,the following main research results are obtained:（1）Preparation and catalytic performance of modified Na Y zeolite molecular sieve encapsulated tungstophosphoric acid catalyst.Using Na Y zeolite molecular sieve as the carrier and sodium tungstate as the tungsten source,a modified Na Y zeolite molecular sieve encapsulated tungstophosphoric acid catalyst was prepared by one-step and two-step methods,and the esterification reaction of oleic acid and methanol was used as the catalyst evaluation model to convert The rate is the index of investigation,and the influence of the p H of Na Y zeolite molecular sieve modified slurry,the amount of sodium tungstate added and the phosphorylation time on the catalytic performance of the catalyst was investigated.The test results show that the optimal preparation conditions of modified Na Y zeolite molecular sieve encapsulated tungstophosphoric acid catalyst are:the modified slurry p H is 3,the addition amount of sodium tungstate is 65%,and the phosphorylation time is 6 h.After the chemical reaction,the conversion rate of oleic acid is the highest,which can reach 64.5%.After the encapsulation of tungstophosphoric acid with Na Y zeolite molecular sieve as the carrier,the ratio of the amount of the prepared encapsulated catalyst silicoalumina increased from 2.40 to 2.65 for Na Y zeolite,and the relative crystallinity of PW-Na Y catalyst was dropped to 34.6%.Under better process conditions,the oleic acid conversion rate remained at 57.8%after repeated use for4 times.（2）The preparation and catalytic performance of modified USY zeolite molecular sieve encapsulated tungstophosphoric acid catalyst.Using USY zeolite molecular sieve as the carrier and sodium tungstate as the tungsten source,a modified USY zeolite molecular sieve encapsulated tungstophosphoric acid catalyst was prepared by one-step and two-step methods,and the esterification reaction of oleic acid and methanol was used as the catalyst evaluation model to convert As an index,the effects of the p H of the USY zeolite molecular sieve modified slurry,the amount of sodium tungstate added,and the phosphorylation time on the catalytic performance of the encapsulated catalyst were investigated.The test results show that the best preparation conditions of modified USY zeolite molecular sieve encapsulated tungstophosphoric acid catalyst are:modified slurry p H 3,sodium tungstate addition 65%,phosphorylation time 6 h,under these conditions catalyzed oleate After the chemical reaction,the conversion rate of oleic acid was the highest,being 96.2%.After encapsulation of tungstophosphoric acid with USY zeolite molecular sieve as the carrier,the amount of silicon-aluminum material of the catalyst increased to more than 10,and the relative crystallinity of the PW-USY catalyst fell to 67.2%.The N₂ adsorption-desorption results show that the catalyst has the characteristics of a typical IV-type N₂ isothermal desorption curve and a wide H4 type hysteresis curve.The NH₃-TPD results show that the measured acid amount of the catalyst is at weak acid sites and strong acid sites.0.043 and 0.032 mmol·g^-1.Under better process conditions,the conversion rate of oleic acid is 84.6%after repeated use of the catalytic oleate reaction for 6 times.（3）Using fatty acids and methanol obtained from the hydrolysis of kitchen waste oil as raw materials,PW-Na Y and PW-USY catalysts are used to catalyze fatty acids to produce biodiesel.Mainly using fatty acid and methanol as raw materials,and using the conversion rate of fatty acid as the index,the catalytic performance of the two catalysts was studied.And conduct kinetics research,using a first-order reaction kinetics model to perform kinetic fitting on the preparation of biodiesel.The test results show that when using PW-USY catalyst to catalyze fatty acid to prepare biodiesel,the conversion rate of fatty acid reaches 96.7%.The process optimization results of PW-USY catalyst for the preparation of biodiesel catalyzed by fatty acids are:under the conditions of an acid-alcohol mass ratio of 1:4,a catalyst dosage of 6%,a reaction temperature of 120°C,and a reaction time of 6 h,the fatty acid conversion rate can reach96.7%.The product value of biodiesel obtained under optimal conditions was analyzed using acid value,density and viscosity as indicators.The saponification value of the biodiesel was 5.5mg KOH·g^-1,density was 0.8861 g·cm^-3,and kinematic viscosity was 7.84 mm²·s^-1.The calculated activation energy Ea was 36.76 k J·mol^-1,and the frequency factor A was 6.66×10^-2min^-1.Based on 120℃,a dynamic equation was obtained:x=1-1/（e^0.0088t）.Based on the above test results,modified Y-type zeolite is used to prepare encapsulated tungstophosphoric acid catalyst,and the catalyst is used in oleate esterification process and biodiesel preparation,which has good catalytic activity and stability.It can provide data support for the preparation of encapsulated catalyst and its use in the production of biodiesel.