GC Determination of 6 Components in Fluid Catalytic Cracking Light Gasoline and Its Etherified Products

GC separation and determination of 6 components, i.e., methanol, isopentane, 3-methyl-1-butene, 2-methyl-1-butene, 2-methyl-2-butene and tert-amyl-methyl ether in fluid catalytic cracking (FCC) light gasoline and its etherified products were applied using a chromatographic column of DB-1 (150 m length) under the mode of programmed temperature elevation. Contents of the 6 components were calculated by the method of correction-normalization based on the values of peak area A_i and relative pesponse factors R_i of the related component, taking the relative atomic masses of 12.011 for carbon and 1.008 0 for hydrogen in the calculation of the relative response factors. The detection limit of methanol was 0.002%, and the detection limits of the remainder 5 components were same as 0.001%. A sample of etherified light gasoline of FCC was analyzed by the proposed method, giving RSDs (n=6) of 0.82%, 0.64%, 1.1%, 0.54%, 0.33% and 1.3% for the 6 components respectively. Recovery of the 6 components was tested by standard addition method, giving results in the range of 88.9%-99.0%. The proposed method was used to evaluate the capacity of the catalyst of the catalytic cracking installation. In this case, samples were taken from the substances separately at the outlet of pre-reactor, at the top of the etherification distillation tower and at the outlet of post-reactor, and analyzed by the method for their components. As isopentane did not take part in the FCC process, the conversion rates of isoamylene of the technology process could be calculated on the base of the ratio of isoamylene to isopentane at the inlet and outlet of each reactor. It was found that the conversion rates of isoamylene in the pre-reactor, in the etherification distillation tower and in the post-reactor were found to be 66.5%, 76.1% and 37.5% respectively. The total conversion rate of etherification was 95.0%.