| EU-1 zeolite with framework type EUO, which consists of 10-membered ring (10-MR) channels with deep side-pockets circumscribed by 12-MRs which make it a useful catalyst for shape selective reactions such as hydrocarbon’s selective cracking and xylene isomerisation, especially showed excellent performance in xylene isomerization reactions, so it has become the preferred catalytic material for the xylene isomerization.For zeolite catalyst, the crystal size of zeolite is an important factor that affects the activity of reaction and the selectivity for products. Compared with micro-size EU-1 zeolite, small crystal EU-1 zeolite possesses high exterior surface area and shorter pore pathway, so there are lots of apertures and acid sites exposed at the outside surface of the crystal. Thus small crystal EU-1 zeolite has excellent diffusion performance and it can provide anti-carbon deposition property and have longer catalytic life in the catalytic reaction. In this paper, small crystal EU-1 zeolite was successfully synthesized by hexamethonium dihydroxide (HM(OH)2) which provided alkali source and template in the crystallization condiction of adding directing agent to synthesis system and ageing at low temperature. Compared with adding organic long chain polymer, this synthetic method was low cost, and was a green synthetic method, because the desired product with a low sodium and bromine ion content that did not need ion exchange can be used directly in industrial catalytic retaction. In order to optimize the synthesis conditions, the experiments also investigated the influence of different factors on products, such as template addition, silicon to aluminum ratio, crystallization temperature and time, and the samples were characterized by XRD, FT-IR, SEM, N2-adsorption/desorption, NH3-TPD and so on.Firstly, in this paper, the effect of raw material ratio for EU-1 zeolite was studied in detail. The results showed that using hexamethonium dihydroxide as alkali source, EU-1 zeolites with a range of different silicon to aluminum ratio can be obtained, silicon to aluminum ratio can reach more than 300 easily, and alkali to silicon ratio must be controlled from 0.04+A to 0.12+A. Secondly, synthetic method and technology was optimized. On the basis of directing agent providing a large number of nucleation, the crystals were grown slowly that the crystal size can be reduced under the conditions of low aging temperature. Besides, with addition of directing agent, the amount of template was greatly reduced and the cost was saved.Intergrowth zeolite has good collaborative function showing a good catalytic performance that single molecular sieve or the mixture of mechanical properties don’t have.This paper adopted silicion aluminum method using SAPO-34 zeolite as aluminum source for synthesising SAPO-34/EU-1 intergrowth zeolite, and investigated the effects of addition of SAPO-34 zeolite on the products which were characterized by XRD, SEM, NH3-TPD. In addition, catalytic performance of materials were investigated with methanol conversion as a probe reaction. The results showed that the synthetic samples were EU-1 zeolites.With the increase of the amount of SAPO-34 zeolite, the weak and strong acidity of EU-1 zeolite were stronger than the tradition methog for synthesis of EU-1 zeolite. This materials had a certain activity,the methanol conversion over the material was 100%,the mass fractions of ethylene,propylene and butylenes selectiveity in the products was 51.2%、32.2%.In addition, a group intergrowth zeolite was systemtically studied hydrothermal stability. The results showed that this EU-1 zeolite had good hydrothermal stability. After a long period of hydrothermal treatment, while the degree of crystallinity of the zeolite decreased, they still had the crystal type and crystal appearance.At the same time, the catalytic selsctivity and catalytic life has decreased slighely, but they showed good hydrothermal stability. |
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