Synthesis Of Pyridine And Picolines From Alkanol And Ammonia

Pyridine bases including pyridine and picolines, which are important raw materials in chemical industry, especially in the field of fine chemicals, are extensively used in a number of areas, including pesticides, pesticide intermediates, pharmaceutical intermediates, pharmaceutical products, animal feed, etc. In recent years, the application domain of pyridine and picolines has been expanding. The production of pyridine bases is made by tar extraction and the way of synthesis. The former method is out in foreign countries because of its serious pollution, but our contry mainly uses it; the later one is mainstream production method at abroad, whose production rout is using formaldehyde, acetaldehyde and ammonia, but the cost is high and poisonous. So far, there have been seldom companies and joint ventures producing pyridine bases using the latter method. But their prodtion is little, which can not satisfy the demand of the markets, so our country is depending on imports in pyridine and pyridine derivatives. As a result, research in producing pyridine and pyridine derivatives is urgent and necessary.Based on the background above, our paper made research on a new method. The source of synthesizing pyridine and pyridine derivatives used by our group is bulk chemical feedstock such as methanol, ethanol and ammonia, which is both cheap and sufficient in domestic market. As a result, making research on synthesizing pyridine and pyridine derivatives has a broad market prospect, which also satisfies the request of continuable development; meantime, it will take an important part in the development of the field of fine chemical industry.In this paper, the catalysts studied were modified by metal salts by the method of impregnation. Activity test were carried out over the prepared catalysts. The experimental results were listed as follows:1. In our work, a series of catalysts prepared by impregnation over several carriers, such as Na-ZSM-5zeolites, H-ZSM-5zeolites, alumina and Y zeolites, were systematically investigated.The results of the experiments showed that the series of ZSM-5zeolites of high regularity performed best, H-ZSM-5especially, and the yield of pyridine bases is6.12%.Numerous catalysts were prepared by impregnation of different metal salts over the same carrier. Their activity was tested under the same condition, and the catalyst modified by bismuth salt performed best, and the yield of pyridine bases is21.66%.As we confirmed bismuth salt as the best modified metal salt, a series of catalyst were prepared with the same mass ratio of bismuth salt over H-ZSM-5with different Si/Al ratios. The results showed that H-ZSM-5with Si/Al ratio of100was the most suitable carrier, and the yield of pyridine bases is30.42%.By using sing-facor method, we found that the catalyst loaded20%wt. bismuth salt showed the highest activity, and the yield of pyridine bases is39.04%.2. By using the single factor and the simplex optimization method, the formation of pyridine and3-metheylpyridine from methanol, ethanol and ammonia was optimum at29.88%pyridine yield,2.27%2-mehtylpyridine yield and7.62%3-methylpyridine yield over20%Bi/HZSM-5(100) at410℃,2:1:3the mole ratio of ethanol to methanol to ammonia,0.75g of catalyst amount, the air as the carrier gas and10ml/min carrier gas flow rate, LHSV=0.81h-3. The surface area, pore size distribution, skeleton structure, pore structure,, acidic property of the catalysts had been characterized by means of modern techniques such as X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR), NH3temperature programmed desorption (NH3-TPD), N2-adsorption at low temperature. We founded that as we used HZSM-5(100) as the carrier, the surface areas, acid amount, acid strength and pore sizes of the catalysts changed regularly with the load of bismuth salt growing.4. Preliminary study was made on the mechanism of the synthesis of pyridine and3-methylpyridine from methanol, ethanol and ammonia. We guessed that the methanol and ethanol were firstly oxidized to formaldehyde and acetaldehyde, and then formed pyridine and picolines with ammonia later.