| α-tetralone is an important synthesis intermediate,with wide application in antidepressant Sertraline,countraceptives,pesticides carbaryl and plastic softener. Reported methods showed thatα-tetralone can be synthesized by tetralin oxidation or F-C reaction of benzene andγ-butyrolactone under AlCl3 catalysis.However,Tetralin oxidation method has a problem of low conversion and AlCl3 is corrosive,polluting and it can not be reused,which is not favored by green chemistry.Recently,Zeolite has received much attention in F-C reaction.Zeolite is a kind of important solid acid with certain acidity,regular pore structure and high specific surface area,and has found wide application in petrochemicals and fine chemical synthesis.The physicochemical properties of zeolite can be modified by certain methods,leading to a change in acidity and pore structure.Zeolite is of high thermal stability so that it can be regenerated by O2 oxidation at high temperature which will reduce the cost.In this paper we have investigated the vapor phase reaction of benzene withγ-butyrolactone.The properties of catalysts are systemically characterized.The results are discussed and a possible reaction mechanism is proposed.The main results are as follow:1.ZnCl2 was supported on the surface ofγ-Al2O3 and active carbon.Heteroploy acid H3PW12O40 was supported on the surface ofγ-Al2O3.The catalysts were evaluated in a fix bed reactor.The result showed that:①33.3%ZnCl2/γ-Al2O3 and 33.3%ZNCl2/C are highly effective in the vapor phase reaction of benzene withγ-butyrolactone while 33.3%H3PW12O40/γ-Al2O3 do not catalyze the reaction.②By 33.3%ZnCl2/γ-Al2O3 catalyst,in the temperature range of 300-360℃,the conversion is inversely correlated with temperature.The selectivity and yield ofα-tetralone is low.Besides propylbenzene(including isopropylbenzene and n-propylbenzene),2-butenoic acid andα-tetralone,Over 30%of the product are unexpected and the reaction mechanism is very complex.2.The Acidic zeolites are apparently effective for the vapor phase reaction of benzene withγ-butyrolactone.The result may varied much among zeolites,but the major products are propylbenzene,2-butrnoic acid andα-tetralone.HZSM5 provides a new way for the synthesis ofα-tetralone with high selectivity and stability. The effects of reaction condition on conversion and selectivity are discussed and a possible reaction mechanism is proposed.The steam treatment,thermal treatment and phosphoric acid modification are investigated.The results are as follow:①HZSM5 is highly effective for the synthesis ofα-tetralone and the best silica to alumina ratio is 50.The deactivated HZSM5(Si/Al=50) can be regenerated simply by air or O2 oxidation and its activity is recovered.②The steam treatment,thermal treatment and phosphoric acid modification exert a positive influence on the activity and selectivity,but no apparent effect is observed on the selectivity.The steam treatment and thermal treatment showed good activity and stability.③The possible reaction mechanism for vapor phase reaction of benzene with γ-butyrolactone is:γ-butyrolactone opens the ring and reacts with benzene to form 4-phenylbutyric acid by intermolucular alkylation;4-phenylbutyric acid producesα-tetralone by intramolucular acylation.The vapor phase reaction of benzene withγ-butyrolactone is proposed as E-R mechanism.Propene and 2-butenoic acid may be the precursors for the carbon deposition to make the catalyst deactivated.3.The acidic zeolites are characterized by NH3-TPD,BET,XRD and O2-TG. The result showed that:①For HZSM5 with different silica to alumina ratio,the acidic amount is inversely correlated with silica to alumina ratio.②The steam treatment,thermal treatment and phosphoric acid reduced the acidic amount of zeolite(both weak acidic center and strong acidic center),but these treatment do not affect the bulk phase structure of HZSM5.③After the deactivation and regeneration,HZSM5(Si/Al=50) showed no change on the bulk phase structure so that the main reason for deactivation is carbon deposition on the surface of catalyst.
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