Regeneration Of Deactivated Hierarchical La/HZSM-5 By NTP And Catalytic Upgrading Of Bio-oil

Catalytic pyrolysis of biomass is one of the important ways to convert biomass into liquid fuel with the advantages of high efficiency and easy operation.However,the catalyst employed for catalytic upgrading of bio-oil is prone to coking and deactivation.Therefore,how to regenerate the catalyst and increase the cycle of use has become one of the cores for the technology.Although the traditional regeneration method of coke burning can remove the coke of deactivated catalyst,it is easy to arise the phenomenon of"fly temperature"at a high temperature environment,which is likely to causes the collapse of skeleton structure for catalyst.Therefore,the regeneration of deactivated catalyst by non-thermal plasma is proposed in this paper.The coke on deactivated catalyst will be removed at a relatively low temperature to avoid the sintering deactivation of catalyst due to high temperature.The main research works are as follows:?1?Rape straw was selected as the biomass raw material,and hierarchical La/HZSM-5was employed as the catalyst for the experiments of online catalytic upgrading of pyrolysis vapor from rape straw.Deactivated hierarchical La/HZSM-5 with different times of use were characterized by TG?XRD?BET?FT-IR?Py-IR?SEM methods and the soluble coke on the deactivated catalyst were characterized by GC-MS methods to analyze the deactivation discipline.The results showed that after hierarchical La/HZSM-5 was used once,most of its catalytic activity had disappeared,and a large amount of coke deposited on the surface and in the pores with the content of 8.55%.The specific surface area and pore volume of the catalyst decreased sharply due to the large area of coke covering and clogging,which were 30.0%and29.8%of fresh catalyst respectively.The acid properties on the catalyst also decreased sharply,which was 30.5%of fresh catalyst,but the crystal phase structure and skeleton structure were not destroyed.After hierarchical La/HZSM-5 was used twice continuously,its specific surface area,pore volume,and acid properties further decreased,but the crystal phase structure and skeleton structure still remained undamaged.There were many kinds of compounds in soluble coke,mainly including phenols,ketones,aldehydes and hydrocarbons.?2?The working parameter of NTP generator was optimized,and the regeneration of deactivated hierarchical La/HZSM-5 by non-thermal plasma at different temperatures were carried out.Regenerated hierarchical La/HZSM-5 were characterized by TG?XRD?BET?Py-IR?SEM methods and the concentration of CO₂ and CO in the regeneration exhaust gas was monitored by gas analyzer to analyze the effect of temperature on the regeneration effect.The results showed that NTP generator achieved the best performance with the oxygen flow rate of 3 L·min^-1,discharge voltage of 17 kV,discharge frequency of 8 kHz.When regeneration temperature was 250?,deactivated hierarchical La/HZSM-5 had the best regeneration effect,and 97.4%of coke was removed.The recovery of acidity,specific surface area and pore volume of the catalyst were the highest.In addition,the crystal structure and skeleton structure of the catalyst were not destroyed by NTP.When regeneration temperature rose to 300?,more O₃decomposes.At this time,the decomposition of O₃ had become the limiting factor for the oxidative decomposition of coke.The peaks of CO₂ and CO concentration in the exhaust gas decreased,and the regeneration effect of deactivated hierarchical La/HZSM-5 declined.?3?The experiments for online catalytic upgrading of bio-oil over regenerated hierarchical La/HZSM-5 were carried out.The physicochemical properties of bio-oil organic phase were tested by the pH meter,calorimeter,capillary viscometer and elemental analyzer.The composition of bio-oil organic phase were tested by FT-IR and GC-MS methods to analyze the catalytic performance recovery of regenerated catalyst.The results showed that the main components of bio-oil organic phase included hydrocarbons,phenols,aldehydes,ketones,furans,acids compounds,and the main distribution of carbon chain length was between C7^C10.When regeneration temperature was 250?,the catalytic performance of regenerated hierarchical La/HZSM-5 was the best.The bio-oil produced by R-250 had the highest heating value(36.48 MJ·kg^-1),the highest hydrocarbon content?40.51%?,and the lower content of carbonyl oxygenates.The physicochemical properties of the bio-oil produced by R-250 were closest to those of the bio-oil produced by fresh catalyst.