Study On The Preparation Of High-grade Biofuel By Pyrolysis Of Waste Clay Oil With Seaweed Char Based Catalyst

With the increasingly serious energy and environmental problems,it is of great practical significance to use industrial waste as a raw material and to prepare high-grade biofuels with renewable resource carbon catalysts.In this paper,the waste clay oil produced by the oil industry was used as raw material to prepare a good catalytic effect of seaweed char-based catalyst using macroalgae:hizikia fusifarme,and the pyrolysis characteristics of waste clay oil and the mechanism of the effect of seaweed char-based catalyst on the pyrolysis products were investigatedFirst,this paper studies the pyrolysis characteristics of waste clay oil through TG-DTG and reaction kinetic analysis,and shows that the pyrolysis process of waste clay oil can be divided into two stages.The first stage is 180-380℃,which is mainly due to the initial cracking of the oil and fat component.The second stage is 380-550℃,which is the main decomposition stage of long-chain fatty acids and fatty aldehydes.Furthermore,Py-GC-MS was used to analyze the main products of pyrolysis volatiles at different pyrolysis temperatures,and the effect of temperature on them.The results show that the main chemical composition of the product is carboxylic acids,hydrocarbons,esters,and a small amount of alcohols and carbonyl compounds;at the same time,as the pyrolysis temperature gradually increases,the content of hydrocarbons increases,and the content of carboxylic acids decreases.It is proved that the increase of pyrolysis temperature is beneficial to promote the decarboxylation reaction,and at the same time,the cyclization reaction may occur during the pyrolysis processSecondly,on the basis of analyzing the pyrolysis characteristics of waste clay oil,a fast bed pyrolysis experiment study was carried out on it,and the direct pyrolysis of waste clay oil by means of FTIR,NMR,GC-MS and GC-TCD/FID The product was analyzed.FTIR and NMR mainly analyzed the chemical composition of bio-oil in the rapid thermal cracking of waste clay oil,and confirmed the presence of a large number of linear aliphatic compounds including linear hydrocarbons,carboxylic acids,esters and carbonyl compounds,and The pyrolysis products are similar;and GC-MS analysis also found that there are a large number of fatty acids in the products,indicating that the structure of long-chain fatty acids is relatively stable and cannot be completely decomposed at high temperatures;GC-TCD/FID was used to analyze the gas-phase products during pyrolysis It is concluded that decarbonylation,dehydrogenation,and decarboxylation reactions occur during pyrolysis,and the decarbonylation reaction dominates during the deoxygenation process.At the same time,with the deepening of the reaction,the carbon chain is further broken,forming a large amount of small molecule gas,which increases the gas-phase products.In addition,using oleic acid as a model compound,the pyrolysis reaction mechanism of unsaturated fatty acids was further studied,and possible reaction paths were proposedThen,the basic characteristics of the prepared seaweed char-based catalyst were characterized.The surface structure characteristics of the seaweed char-based catalyst were analyzed,the graphitization degree of the char-based catalyst was investigated,and the pore structure of the char-based catalyst was analyzed.Using KOH to activate the catalyst and using Cu(NO3)2 to modify the catalyst,it was found that increasing the temperature can promote the activation effect of KOH,enhance the graphitization degree of seaweed char,reduce the disorder,and increase the specific surface area of seaweed char.The prepared seaweed char presents a multi-level pore structure,with micropores,mesopores and macropores,and the activation temperature has little effect on the pore size,the pore size distribution range is relatively concentrated at about 5nm,and the average pore size is about 3nm.The specific surface area of seaweed char prepared by activation at 800℃ reaches the maximum value(1227.74 m2/g),which is a good catalyst carrier.Through modification,the metal copper particles are evenly loaded on the seaweed char,which has a good metal active centerFurther,using seaweed char to carry out catalytic pyrolysis and upgrading experiments on waste clay oil.The effects of seaweed char-based catalysts on the liquid phase and gas phase products in the reaction of catalytic pyrolysis of waste clay oil were studied,and the catalytic effects were compared with conventional catalysts.The better performance seaweed char catalysts were selected.Studies have shown that the seaweed char-based catalyst without metal modification has a decarboxylation effect,which effectively reduces the content of acids in the liquid phase product and increases the content of hydrocarbons,but also greatly reduces the yield of the liquid phase product,thereby generating A large number of small molecular hydrocarbons,especially those below C4 have been significantly improved.The decarboxylation effect of Cu-modified algae charcoal is obvious,and the copper particles distributed on the algae charcoal form active sites,which effectively reforms the pyrolysis volatiles and promotes the production of hydrocarbons,especially aromatic hydrocarbons Therefore,the modified seaweed char-based catalyst has a certain aromatization effect.At the same time,the hydrogen content in the gas-phase product decreased significantly,which may be due to the hydrogenation reaction under the action of catalysisFinally,the effects of 15%Cu/Y800(seaweed char catalyst),MCM-41 and CaO on the catalytic upgrading of waste clay oil were found.Compared with the carbon catalyst,the decarboxylation effect of MCM-41 is weaker,but it can enhance the decarbonylati on The effect of CaO can use its own alkali to neutralize the acidic substances of pyrolysis volatiles,significantly reduce the carboxylic acid in pyrolysis oil,and generate a large amount of aromatic hydrocarbons,but aromatic hydrocarbons contain polycyclic aromatic hydrocarbons,the pyrolysis products There is a certain impact on the combustion characteristics.In summary,15%Cu/Y800 catalytic pyrolysis to upgrade waste clay oil has certain advantages for the preparation of high-grade biofuels.