Experimental Study On Catalytic Cracking Of Waste Oil

In order to study the catalytic pyrolysis characteristics of waste cooking oi,this paper finished some experimental research work.The research results are as follows:The composition of the gaseous products from the thermogravimetric analyzer during waste cooking oil pyrolysis were investigated using the TG–FTIR-MS coupling technique and TG-GC/MS.The thermal cracking process and thermal cracking characteristics of the waste cooking oil were discussed.The results indicated that the pyrolysis process can be divided into three stages:the first stage was the breakage of the C-O bond of triglyceride to formthe diacylglycerol,monoglyceride,fatty acid and aliphatic aldehyde;the second stage was through C-C bond cleavage,C-O bond cleavage and decarboxylation of esters and fatty acids to release fatty acids,aliphatic aldehyde,aliphatic ketones,hydrocarbon and CO₂;the third stage was decarboxylation reaction of fatty acid and Diels-Alder reaction of alkenes to form hydrocarbon and CO₂.Multichannel pyrolysis pathways of hogwash oil and radical-related evolution mechanisms of the products were examined by a combination of thermogravimetry–Fourier transform infrared（TG–FTIR）spectroscopy and pyrolysis–gas chromatography/mass spectrometry（Py–CG/MS）.The results revealed that the decomposition mainly focus on the fission of the C-O bond between the glycerol backbone and fatty acid chain of triglycerides in waste cooking oil in the temperature range of 200³60°C,associated with the production of RCOO·,ethers and glycerol.the decomposition mainly focus on the thermal cracking of the RCOO·radical,where the cleavage corresponds to the fission of theα,β–C bond,and decarboxylation,with CO₂,alkanes,alkenes,and fatty acid as the main compounds,which are released between 380°C and 500°C;at temperatures of greater than 500°C,The major reactions occurring during the pyrolysis of waste cooking oil included the Diels–Alder reaction,elimination of ethylene,and decarboxylation.with the main organic species products include aromatics,alkenes,and alkanes.Five catalysts of MCM-22,NaY,ZSM-5,MCM-41,SBA-15 and MCM-22 were selected.The catalytic pyrolysis products of the waste cooking oil were analyzed by TG-FTIR combined with Py-GC/MS.The product obtained by catalytic pyrolysis of the waste oil is obtained,and the content of the ketone substance in the product is lower than that of the non-catalytic pyrolysis of the waste cooking oil.MCM-41 has a small pore size,so there are high content of macromolecular substances in the product,and it has a good deoxidation effect.The ZSM-5 catalyst has a strong aromatization ability.The NaY catalyst has good selectivity to olefin alkanes and can achieve deoxidation effect well.MCM-22 has poor catalytic activity for pyrolysis of the trench oil and poor decarboxylation ability.