Biofuel From Catalytic Cracking Of Lipid Over Bi-component Supported Molecular Sieve Catalyst

Biofuel produced from lipid has shown potential as the alternative technology of energy production to deal with the rapid depletion of available petroleum resources and its associated environmental issues.Catalytic cracking of lipid?CCL?for making biofuel has drawn enormous attention.Clearly,the nature of catalysts and lipid plays an important role in the physicochemical properties of biofuels.Thus,in this paper,molecular sieves with suitable pore structure and acid strength have been used for CCL in a fixed-bed reactor.La and Fe have been supported on molecular sieves for adjusting the acid sites to reduce the aromatics content of biofuel.The composite catalysts have been prepared by mechanical mixing with basic catalyst and molecular sieves for reducing the acid value of biofuel.Moreover,the influence of the nature of lipid on CCL has been studied.The main results are as follow:Si-MCM-41 was suitable for catalytic cracking of soybean oil for biofuels which is in the range of diesel,due to its well-ordered one-dimensional hexagonal structure and moderate acidity.The 66.36 wt.%yield of organic liquid product?OLP?with low acid value(9.22 mgKOH·g^-1)and oxygen content?4.74 wt.%?,as well as high calorific value(44.73 MJ·kg^-1)was achieved at the suitable catalytic cracking conditions(the ratio of lipid to catalyst was 6:1,temperature was 460°C,weight hourly space velocity?WHSV?was 6.69 h^-1.)However,the aromatics content reached 37.51 wt.%,which was higher than the limit?15 wt.%in diesel?.Thus,it is necessary to reduce the aromatics content of OLP.La-Fe modified Si-MCM-41 catalysts?La-Fe/Si-MCM-41?was synthesized by a wet impregnation method for adjusting the acid site of the catalysts.The results showed that the catalyst supported with La-Fe bi-component exhibited the better effect on reducing aromatics content.with the increase of B/L value,the aromatics content increased,while the content of oxygenated compounds decreased,indicating that Br?nsted acid sites were the major active sites for deoxygenation and aromatization reactions.The Br?nsted acidity and strong Lewis acidity of La-Fe/Si-MCM-41 have been decreased to 5.86 and 9.81?mol/g as the La-Fe loading increasing to 6 wt.%,resulting in the aromatics content of OLP reduced to 14.52 wt.%which is lesser than the limit.While the fatty acids content of OLP reached 16.67 wt.%,leading to the high acid value(35.20 mgKOH g^-1)of OLP.The CaO/LFM-6 composite catalysts prepared by mechanical mixing with CaO and LFM-6 have been applied to catalytic cracking of soybean oil.The results indicated that CaO acted as a catalyst,an absorbent and a reactant for upgrading the liquid and gaseous products simultaneously.The yield of OLP produced from catalytic cracking of soybean oil over LFM-6-C-3 reached 73.40 wt.%at 460°C and 6.69 h^-1 when the ratio of lipid to catalyst was 3.75:1.The hydrocarbons content reached 70.89 wt.%,while the aromatics content was 12.31 wt.%,thereby,the calorific value of the OLP reached 44.14 MJ·kg^-1.Meanwhile,the fatty acids content was 2.76 wt.%,as a result,the acid value of the OLP was10.12 mgKOH·g^-1.Moreover,the flammable gas content of gaseous product increased to 92.30%with the decrease of CO₂ content to 7.70%.Shea butter consisted of glycerol tristearate?47.32 wt.%?and glycerol trioleate?44.63 wt.%?,suiting for producing biofuels by catalytic cracking.The biofuel with desired properties has been achieved by catalytic cracking of shea butter over PMA-32composite catalyst prepared via extruder with the mass ratio of Si-MCM-41/Al₂O₃ was3:2.Transesterification of shea butter with methanol as a pretreatment step has been conducted.The result demonstrated that shea butter methyl ester was more suitable as the feedstock for producing biofuel by catalytic cracking technology.The geometry and size of shea butter methyl ester contributed to the diffusion of molecular in the pore of catalyst and slowing down the deactivation of catalyst.In addition,the influence of unsaturated fatty acid methyl ester on the formation of aromatics was grester than the acidity of the catalysts.The 67.90 wt.%yield of OLP with low acid value(5.15mgKOH·g^-1)and oxygen content?1.55 wt.%?,as well as high calorific value(45.31MJ·kg^-1)was achieved at the suitable catalytic cracking conditions(the ratio of lipid to catalyst was 5:1,temperature was 450°C,WHSV was 12.00 h^-1.)The composition of OLP was similar to the diesel fuel,the hydrocarbon content reached 84.69 wt.%,mostly C₁₅^C₁₈ linear alkanes?42.49 wt.%?,while the aromatics content was 17.86 wt.%closed to the limit.This work provided a theoretical basis for the scientific research and technical development of biofuel produced from catalytic cracking of lipids.