Small Grains HZSM-5 Zeolite Catalytic Performance Of Methanol To Propylene And Butene For Coupling

Propylene is one of fundamental and important organic chemical raw materials of petrochemical industries on a global scale, which used for producing polypropylene, acrylonitrile, and propylene oxide, etc. In recent years, with the fast development of demand for propylene derivatives, the contradictory between propylene1supply and demand is becoming more and more prominent. Nowadays, propylene is mainly produced from steam cracking and fluid catalytic cracking (FCC), which were limited due to the shortage of petroleum resources and the production technology condition in China. Beyond that, other routes for the production of propylene (such as, methanol to propylene (MTP), olefins disproportionation and the dehydrogenation of propane) show some disadvantages, such as, the coking and deactivation of catalyst, tough experimental conditions and high raw material costs. Therefore, it is necessary to explore an alternative approach to increase propylene production.The reaction of coupling of C4hydrocarbon and methanol to propylene was benefit for the balance of heat and energy. The coupling reaction not only enhanced the capacity of the conversion of butene cracking, improved the yield of propylene, but also simplified the process of reactor design and cost savings, which indicated a new direction for the utilization of the lots of excess methanol and C4hydrocarbon.This research work of this paper is composed by the following four components.1. The prepared of superfine HZSM-5catalyst. A series of superfine HZSM-5catalysts with different crystal size were synthesized by different methods. The catalytic performance for the coupling conversion of methanol and1-butylene to propylene was investigated on these catalysts. The superfine HZSM-5catalysts with different silica alumina ratio (respectively120,150,200,250,300) were synthesized by the optimal preparation method among four preparation methods.2. Characterization of these catalysts. The X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), N2isotherm adsorption-desorption (BET), Scanning electron microscopy (SEM) and Programmed desorption of ammonia (NH3-TPD) were used to characterized the bulk structure, surface properties and acidity of superfine HZSM-5zeolite. The catalytic performance of size effects and acidity effects on the coupling conversion of1-butylene and methanol to propylene were investigated based on the superfine HZSM-5zeolite.3. The catalyst performance evaluation. The catalytic performance on the reaction of1-butylene and methanol to propylene was investigated based on the superfine HZSM-5zeolite in a continuous fixed bed reactor. Firstly, the effect of crystal size and silica alumina ratio on the properties and catalytic performance of superfine HZSM-5catalysts was investigated. Secondly, the influences of molar ratio of reactants, reactive temperature and WHSV on the product distribution in methanol and1-butylene to propylene were discussed, the optimal reaction conditions of obtained.4. The kinetics of the coupling conversion of methanol and1-butylene to propylene was studied. The reaction kinetic parameters of methanol to propylene,1-butylene to propylene and methanol&1-butylene to propylene was compared, the coupling advantage of methanol and1-butylene to propylene was researched. The kinetics law of different reactions was simply studied.The main results are shown as follows:1. The physicochemical properties and the catalytic reactivity of the samples were strongly dependent on synthesis methods. These catalysts of have high catalytic reactivity and stability, due to smaller crystalline size, higher specific surface area and appropriate acidity. The weak and medium acids sites might be responsible for the coupling conversion of methanol and1-butene to propylene. Appropriate acidity was conducive to increase the yield of propylene.2. Under the optimal reaction conditions (823K,1.6g/(mol/h),0.1Mpa, the molar ration of methanol/1-butylene=2:1), superfine HZSM-5(SiO2/Al2O3=200) showed the highest propylene yield of ca.34.4%and good stability in time on stream of6h, due to smaller crystalline size, higher specific surface area and appropriate acidity.3. The coupling reaction of methanol and1-butene to propylene has higher reaction velocity constant and less reaction active energy than the reaction of methanol to propylene and the reaction of1-butylene to propylene. Results show that the coupling reaction of methanol and1-butene promoted the yield of propylene. Based on the above results,①it is shown advantages in the coupling reaction of methanol and1-butene to propylene, not only solved the problem of the steam cracking and fluid catalytic cracking (FCC) strongly depend on petroleum resources, but also keep the balance of reaction heat in order to increase the yield of propylene.②the higher propylene yield of methanol and1-butene to propylene was obtained on superfine HZSM-5zeolite.③the study shows that the coupling reaction of methanol and1-butene to propylene has higher reaction velocity constant and less reaction active energy, which favors the production of propylene.