Reaction Research With Methanol As A Part Of Catalytic Cracking Feed

Considering the increasing demand of light olefins and the lack of petroleum resources, the research of producing light olefins from low added value material was quickly developed. The thesis combined with the FCC (fluidized catalytic cracking) unit in China made a comprehensive and systematic laboratory research about feeding methanol as a part of FCC feedstock to produce more light olefins based on the profounded analysis of the similarity of MTO (methanol to olefins) and FCC.On the basis of analyzing the feature of individual reaction zone of industrial FCC reactor, the influencing factors of methanol conversion on FCC condition were first confirmed. Methanol conversion on FCC condition was researched in pulse mini-scale reactor and laboratory fixed-fluidized bed reactor respectively. Experiments were carried out and the results were discussed adequately to analyse the effects of reaction temperature, ratios of catalyst to methanol, methanol solution feed, space velocity, and the coke content of catalyst to methanol conversion. The results of various reaction conditions on the two experiment device showed that the hightst hydrocarbon yields was about 30m%, and the hightest light olefins selectivities was more than 60m% despite of the difference of experiment device and their optimum conditions. The results also showed that the existance of water can increase the selectivities of light olefins and restrain the coke on catalyst. The hydrocarbon yields and light olefins selectivities were also decreased with the coke increasing on the catalyst.In order to deeply analyse the reaction rules of adding methanol in FCC, the interaction of methanol and individual hydrocarbon on the FCC condition was researched. Experiments were carried out to study the reactions of methanol respectively with n-octane, i-octane, hexanaphthene, benzene, toluene with different ratio on FCC condition. The results showed that the aromatic ring alkylation reaction can obviously take place between methanol and single-ring arene only on the condition of high ratio of arene. Methanol did not react with paraffin, cycloparaffin, but they did interact with each other which promote the conversion of methanol with hydrocarbon which can increase the yields of gas hydrocarbon and coke, and restrain the selectivities of dry gas. The selectivities of C7~C10 hydrocarbon were increased and the selectivities of aromatic were increased remarkably with the increase of methanol proportion.On the basis of above researche, the effects of adding methanol to fraction oil in FCC were studied further.(1) Experiments of adding methanol using various fashions to the catalytic cracking of straight-run gasoline were carried out. The results showed that the gas yields were increased and the selectivities of light olefins were invariant with adding methanol and straight-run gasoline at the same time. The differences of the gasoline composition were that the contents of n-paraffins, iso-paraffins and cycloparaffins were decreased, the contents of olefins increased slightly and the content of aromatics were increased. The results of feeding them respectively were similar with the reaction results of feeding single straight-run gasoline.(2) The results of adding methanol to the course of VGO catalytic cracking showed that, the addition of methanol in FCC promoted the conversions of methanol and hydrocarbon which decreased the DME yield, increased the gas and coke yields, increased the selectivity of gasoline and decreased the selectivities of diesel and the unconverted oil, and the light olefins were maintained. The total selectivities of light olefins were invariant. The changes of the gasoline composition were similar to the results of straight-run gasoline cracking with methanol.In order to fully understand the course of adding methanol as part of FCC feed, experiments were carried out to study the effects of reaction temperature, ratios of catalyst to oil, space velocity, and methanol ratios to the reaction of adding methanol as part of VGO catalytic cracking. The results showed that adding methanol had no change to the rules of this reaction.This paper not only discussed the experimental results above and the possible reaction mechanisms, but also evaluated the effects of adding methanol as part of FCC feedstock. The proper fashion of adding methanol was proposed considering the practical FCC condition. Based on this first research of the technology of integration MTO and FCC and the comprehensive and systematic laboratory experiments, the research would provided important reference to the further research and commercial application in certain degree.