| Zeolite membranes having inorganic crystalline structures with uniform-sized pores of molecular dimensions posess potential in gas and liquid separation at the molecular level, reaction and separation process intergrated membrane reactors due to their superior thermal stability and good erosion resistance. Recently, zeolite membranes also show great potential applications in optoelectronics and chemical sensor. SAPO-34 zeolite (CHA-type) has unique three-dimensional channels with a pore diameter of 0.38 run, which is an excellent catalyst in many important reactions and has potential for light gas separation, giving amazing industrial application prospects in the catalysis and separation processes. Synthesis and application of high performance SAPO-34 and its composite membranes are of great significance. The main task of this paper is to prepare high-performance SAPO-34 and its composite membranes, then build reaction and separation process intergrated membrane reactors for methane dehydro-aromatization under non-oxidative conditions.The present study is mainly comprised of the follwing parts: First, systematic study of the influence of synthesis conditions on the formation of SAPO-34 zeolite was curried out, several means were used to control the growth of SAPO-34 crystals, and different particle sizes of SAPO-34 zeolite seeds were succefully synthesized. Second, SAPO-34 and SAPO-34/carbon membranes were successfully synthesized on the porous ceramic supports, the influences of membrane-forming conditions on the performance of SAPO-34 and their composite membranes were studied, the resultant membranes were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and the gas permeation properties were investigated in detail. At last, methane dehydro-aromatization under non-oxidative conditions in SAPO-34 and SAPO-34/carbon membrane reactors were performed, evaluation of the membrane reactors were curried out and the comparisons of reaction performance in membrane reactors with those in a traditional fixed bed reactor were also studied.(1) Using tetraethyl ammonium hydroxide (TEAOH) as template, the influences of synthesis temperature, synthesis time, aging time, water content, seeds, silica source pretreatment and microwave heating on the formation of SAPO-34 zeolite were investigated. The experimental results indicated that, SAPO-34 zeolite seeds with mean diameters of 1μm, 400 nm and 200 run were successfully synthesized, and the as-obtained SAPO-34 zeolite seeds also showed very narrow size distribution and high crystallinity.(2) High quality SAPO-34 zeolite membranes were prepared on porous ceramic tubular support by conventional heating and microwave heating, respectively. With a feed and permeate pressure of 0.1 MPa at 973 K and using N2 as sweep gas, the H2 permeances were 3.5×10-7 mol·Pa-1·m-2·s-1 and 2.32×10-7 mol·Pa-1·m-2·s-1,and H2/CH4 ideal selectivities were 27 and 45, respectively. The separation performance of prepared membranes also showed long time stability though the temperature was as high as 973 K.(3) SAPO-34/carbon composite membranes were successfully prepared on porous ceramic tubular support using dip coating method. At room temperature and 0.1MPa tras-membrane pressure drop, the H2/CH4 and CO2/CH4 separation selectivities were as high as 112 and 253, respectively. At 973 K, without pressure drop through the membrane and using N2 as sweep gas, the H2/CH4 ideal selectivity was as high as 78, and the H2 permeances was 8.2×10-8 mol·Pa-1·m-2·s-1.(4) Construction of SAPO-34 zeolite membrane reactor and SAPO-34/carbon membrane reacor was performed, and methane dehydro-aromatization under non-oxidative conditions in membrane reactors was curried out. The results showed that, in a SAPO-34 zeolite membrane reactor and SAPO-34/carbon membrane at 973 K, the methane conversions were 16.8% and 17.2%, and the benzene yields were 9.1% and 9.3%, respectively. Compared with traditional fixed bed reactor, the methane conversions were increased by 33.5% and 41.6%, and the benzene yields were increased by 46.7% and 51.8%, respectively.
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