Study On Synthesis Of Microwave Responsive Catalyst And Preparation Of Hydrocarbon-rich Fuel Oil By Catalytic Pyrolysis Of Soapstock

Soapstock is a by-product in the process of alkali refining and deacidification in edible oil production.The main components of soapstock are fatty acid sodium,neutral oil,phospholipids,water and other lipids,and soapstock is one of the best materials for producing high quality bio-oil.Microwave-assisted catalytic pyrolysis of vegetable oil soapstock to produce bio-oil has a good development prospect,but the process has the problems of easy passivation and deactivation of the catalysts and high pressure drop of catalytic bed.To choose the better catalyst to improve the quality of bio-oil,a microwave-responsive catalyst was synthesized as microwave absorbing properties and molecular sieve catalytic function in this paper.The study improved the application system for the microwave-responsive catalyst,completed the microwave pyrolysis in series with the ex-situ microwave catalytic reforming system,realize the microwave synergistic enhancement of catalytic reactions in order to obtain high-quality bio-oil.The main work and conclusions are as follows:1.The composite catalyst was synthesized by microwave synthesis method,and the possibility of SiC foamed ceramics as catalyst carrier was explored.The composite catalyst was characterized by Brunauer–Emmett–Teller analysis,X–ray diffraction,and scanning electron microscopy in this study.The effect of the composite catalyst microwave co-pyrolysis of soybean straw and soapstock on the product distribution and chemical composition in a downdraft system was investigated.The results showed that ZSM-5 grew evenly on the surface of SiC foamed ceramics successfully.In a downdraft system with a catalytic temperature of450 °C,a feed to catalyst ratio of 2:1,and a soybean straw to soapstock ratio of 1:1,the proportions of alkanes,olefins,aromatics,and phenoxy compounds in the bio-oil were 6.82%,4.50%,73.56% and 11.11%,respectively.The composite catalyst has the catalytic performance of ZSM-5 and SiC foamed ceramics,which increases the proportion of aromatic hydrocarbons in the bio-oil and reduces the proportion of oxygen-containing compounds.Moreover,the composite catalyst maintained its activity after reusing several times.2.ZSM-5/SiC catalysts were synthesized with SiC powder and ZSM-5,and were characterized by Brunauer-Emmett-Teller,X-ray diffraction,thermogravimetric analysis,pyridine-infrared spectroscopy,and scanning electron microscopy.The catalysts showed a high heating rate and excellent catalytic performance for pyrolysis vapors,and the product fractional distribution and chemical compositions of bio-oil in a tandem system(microwave pyrolysis and microwave ex-situ catalytic reforming)was examined.36.94 wt% of bio-oil was obtained using the catalyst with20%ZSM-5/SiC under the following conditions: feed-to-catalyst ratio,2:1;pyrolysis temperature,550 °C;and catalytic temperature,350 °C.The selectivities of hydrocarbons reached up to 75.88%.The quality of bio-oil obtained by microwave catalytic reforming is better than that obtained by electric-heating.After five cycles,the activity of the regenerated composite catalyst was retained at 95% of the original catalyst.3.A novel ZSM-5/SiC nanowires-SiC foamed ceramics microwave-responsive catalyst was synthesized,and developed to upgrade the pyrolysis volatiles in a tandem system(microwave pyrolysis and microwave ex-situ catalytic reforming).Microwave-responsive catalyst characterization results showes that the presence of microporous ZSM-5,and the SiC nanowires loosely overlapping growth effectively increased the specific surface area of ZSM-5 growth on SiC foamed ceramics.The GC-MS analysis of the bio-oil showed that the content of hydrocarbons and aromatic hydrocarbons can reach 80.89% and 40.48%,respectively,under the conditions of pyrolysis temperature 550 °C,catalytic temperature 450 °C and catalysts to feedstock ratio 1:2.Under microwave radiation conditions,the microwave synergistic enhancement of catalytic reactions occurred,and the catalytic sites of the microwave-responsive catalysts exhibited better activity and aromatization performance.The catalytic activity of the catalyst after five-cycle regeneration was basically recovered,and the content of hydrocarbons in the bio-oil was still up to76.40%.