Catalytic Performance Of Mental Ions Modified Zeolites On The Transalkylation Of Multi-polyisopropylbenzene With Benzene

Isopropyl-benzene(IPB) is an important organic chemicals, mainly used in the synthesis of phenol and acetone. Industry usually using benzene and propylene in liquid phase alkylation to produce isopropyl-benzene.Diipolyisopropylbenzene(o-diisopropylbenzene(o-DIPB),m-diisopropylbenzene(m-DIPB) and p-diisopropylbenzene(p-DIPB))and trisopropyl-benzene(TIPB) are included in the by-products.Industrial devices usually use the polyisopropyl-benzene and benzene of transalkylaton back into isopropyl-benzene, in order to improve the yield of isopropyl-benzene.Existing research has focused on molecular sieve catalyst for benzene and diisopropylbenzene transalkylation performance study. The literature of enzene and polyisopropylbenzene transalkylation is rarely reported. Conversion rate of triisopropylbenzene is low in the prior art,so the presence of triisopropylbenzene put forward new requirements to catalyst structure of transalkylation and acidic. In addition, there are n-propylbenzene content exceeded in the technology, expensive catalyst and transalkylation temperature is too high,energy consumption and other big problems.At present, there are no reported with different concentrations of chromium nitrate ion exchange of molecular sieve use in the polyisopropylbenzene transalkylation.Based on the previous polyisopropyl-benzene transalkylation experimental,this paper studied on different concentrations of Cr modified β and MCM-49 molecular sieve preparation, and studied the performance of the catalytic in multi-polyisopropylbenzene and benzene transalkylation, the main contents and results are as follows : First of all, prepared Si/Al=25 of CrMCM-49 and Cr βzeolite molecular sieve in the ion exchange method, and characterized by means of XRD,SEM, NH3-TPD and Py-IR. Instruments of molecular sieve structure and morphology,phase and acid were characterized. Found that the chromium nitrate modified zeolite strong acid increased. Instruments of molecular sieve morphology, phase and acid were characterized. With benzene and multi-polyisopropylbenzene as raw material,under conditions of 3.5MPa, 190~240℃, mass space velocity 0.5~1.5h-1, ωB:ωPIPB=0.8~3.1,using high pressure fixed bed reactor, examines the transalkylation catalyst performance. The results showed that the CrMCM-49 and Crβhave better performance.At the same time,0.3% is the optimal modified concentration.The best reaction conditions of Crβ( 0.3%) on polyisopropylbenzene transalkylation is as follows,the temperature is 220 ℃, ωB: ωPIPB=2.3, WHSV=1h-1. Crβ(0.3%) molecular sieve at 190 ℃, conversion rate of diisopropylbenzene compared to the zeolite of Hβ increased by 26.5%. Under the optimum conditions, triisopropylbenzene conversion rate of the Crβ(0.3%) is 50.44%, and Hβ molecular sieve compared, the conversion rate of chromium ion modified molecular sieve triisopropylbenzene increases about 35.51%, isopropylbenzene yield increased 53.53% and Crβ catalytic reaction has no propyl benzene was detected.The best conditions of CrMCM-49(0.3%) on the polyisopropylbenzene transalkylation : the temperature is 190℃, ωB: ωPIPB=2.3, WHSV=1h-1. Under the optimized conditions, CrMCM-49(0.3%) yield of isopropylbenzene is 86.61%, and compared with HMCM-49, transalkylation optimum temperature is reduced by 30℃.triisopropylbenzene conversion rate is still higher than about 11%. Exhibit triisopropylbenzene low temperature conversion activity. content of Cr is one of the factors that influence the effect of catalyst, the optimum temperature for CrMCM-49(0.3%) than CrMCM-49(0.1%) is lower by about 10 ℃, multi-polyisopropylbenzene conversion rate and the yield of isopropylbenzene is similar, and does not have n-propylbenzene detected. The results of the study than reported in the literature of citric acid,magnesium nitrate and lanthanum nitrate and modified molecular sieve catalytic,triisopropylbenzene conversion rate is about 20% higher,reaction temperature decrease 15℃. Chromium nitrate instead of zeolite acid increase, the activity of catalyst increased so much,polyisopropylbenzene conversion rate isincreased and isopropylbenzene yield increased, the reaction conditions become warm.From the point of view of economic, environmental protection and raw material supply, the high crystallinity.MWW structure with low toxicity template was used to replace the six methylene(HMI) to synthesize.In study on Synthesis of MCM-22 and MCM-49 molecular, the existing research concentrated in piperidine, piperazine,cyclohexylamine and dicyclohexylamine template agent and of MWW series of other molecular sieve has not been reported. In recent years, due to the synthesis of MWW zeolite, the traditional template of the template six methylene(HMI) of the price increases, the supply of tension. Therefore, this dissertation has also used low template agent(piperazine(PIP) and hexamethylene imine(HMI) single or compound)synthesis of MWW zeolite molecular sieve, instead of traditional toxic hexamethylene imine template. Find out piperazine in the composite template agent in the maximum amount of the compound, reduce the toxicity of synthetic MWW. The results show that using only single piperazine as templates to synthesize the MWW zeolite is not pure and highly crystalline.The preparation of MCM-49, MCM-56 and ITQ-2template ratio range of n(HMI/PIP) =(0.35~0.18)/(0~0.17), and the preparation of MCM-22 template with a more narrow template.