催化氨氧化2-甲基吡嗪合成2-氰基吡嗪的研究

实验采用自制的Sb2O3-V2O5-TiO2/SiO2型催化剂,研究了以2-甲基吡嗪为原料氨氧化催化合成2-氰基吡嗪的工艺条件,通过对反应温度、液时空速、氨气流率、空气流率等影响因素的考察,确定了适合该催化剂的工艺条件:催化剂装量19mL,进料液时空速0.79h-1,n(2-MP)∶n(NH3)∶n(Air)为1∶5.9∶36,温度370°C。2-甲基吡嗪的转化率达到90%以上,选择性达到70%以上,产品收率达到60%以上。并对其反应原理及工业化问题进行了初步的探讨。     

氨氧化催化合成氰基吡嗪的研究

研究2-甲基吡嗪氨氧化催化合成2-氰基吡嗪的催化反应机理后,可知2-甲基吡嗪是通过一系列的脱氢、氧化生成甲醛吡嗪和羧酸吡嗪然后氰化生成产物的,因此优良的催化剂必须由活性及数目合适的脱氢、供[O]及氰化中心组成.分析了各种氨氧化催化剂后,研制了Sb2O3-V2O5-TiO2/SiO2型催化剂,通过实验分别考察反应温度,进料空速,原料配比的影响.确认在空速0.3h-1,反应温度380℃,配料比为2-甲基吡嗪：氧气：氨气=1：8.5：3（摩尔比）时,2-甲基吡嗪的转化率为70%以上,2-氰基吡嗪的收率为55%以上.与同类催化剂相比,具有反应温度低,空速大等优点,更适合工业化;同时也验证了催化反应机理的合理性.     

催化氨氧化法制备2-氰基吡嗪的研究

开发了一种由VMoOP四元素组成的氨氧化催化剂(V-II型)，用该催化剂在固定床反应器内由2-甲基吡嗪为原料进行气固相接触氨氧化反应制备了2-氰基吡嗪。V-II型催化剂组分中矾、磷的比例是影响催化剂反应活性及选择性的主要因素，矾磷比为1．9时，催化活性最好。探讨了氨氧化反应机理，认为2-甲基吡嗪经过氧化、脱水分别生成了吡嗪羧酸和吡嗪酰胺中间体后最终生成2-氰基吡嗪。正交实验确定了反应的影响因素和最佳条件，结果表明：反应温度是影响产品收率的最主要因素，当2-甲基吡嗪、氨气、空气的投料量分别为0．05mL．min-1，200mL．min-1,1000mL．min-1，反应温度430℃时，2-氰基吡嗪选择性大于90％，单程收率大于87％，产品纯度大于99％。按小试工艺条件放大l00倍中试，结果与小试吻合。     

MoVPO型催化剂上氨氧化合成2-氰基吡嗪

The mechanism of 2-cyanopyrazine prepared from 2-methylpyrazine （2-MP） by catalytic ammoxidation has been explained by the theory of appropriate structure of group. A new catalyst of MoVPO was developed. The effects of catalyst promoter phosphorus and supports were investigated. The catalyst containing P, V and Mo in molar ratio of 1.4 ： 1 ： 0.02 and supported on activated alumina and prepared by impregnation method exhibits good activity and selectivity. Reaction factors such as reaction temperature, space velocity, feed composition and service life of catalyst were investigated. Optimum reaction conditions （the volume space velocity of 0.2h-1, the reaction temperature of 380 ~C and molar ratio of 1 ： 7.8 ： 8 ： 8 for 2-MP, water, oxygen and ammonia） were obtained. Selectivity of 93% and yield of 86% could be achieved under these conditions.     

2-氰基吡嗪市场前景看好

2-氰基吡嗪，英文名称2-Cyanopyrazine；CAS No．19847-12-2；分子式C5H3N3，分子量105，常温下为浅绿色透明液体；熔点20℃，沸点199℃，闪点96℃，密度1．5343，折射率1．5340，是一种重要的化工原料及中间体，在香料、医药等领域具有广泛的用途。如：2-氰基吡嗪与格氏试剂反应可得高级香料，2-氰基吡嗪在医药行业主要用于制备抗结核药吡嗪酰胺。     

V-Ti-O-Mo催化剂气-固相催化氨氧化合成2-氰基吡啶的研究

用混合法制备了含有五氧化二钒(V2O5)、二氧化钛(Ti O_2)和三氧化钼(Mo O_3)的三元催化剂,用于连续气固相氨氧化2-甲基吡啶合成2-氰基吡啶。结果表明,助催化组分三氧化钼(Mo O3)能提高2-氰基吡啶的选择性,当催化剂组成为8.91%(wt)V2O5、85.84%(wt)Ti O_2和5.25%(wt)Mo O_3时2-氰基吡啶的选择性最好。基于改进后的V-Ti-O-Mo催化剂,对2-甲基吡啶的氨氧化反应工艺条件进行了优化,当反应温度380oC、物料配比1:5:3.3:22(2-甲基吡啶/氨气/水/空气,摩尔比)、空速0.15 h-1时,2-氰基吡啶收率达到最优值85.6%。     

急需开发的医药中间体--2-氰基吡嗪

2-氰基吡嗪是生产治疗结核病药物吡嗪酰胺的重要原料.目前仅日本实现了2-氰基吡嗪的工业化生产,主要生产商是日本的KOEI公司.全球2-氰基吡嗪的年需求量约为2600t,年产量约为1600t,市场缺口达1000t/a.我国生产吡嗪酰胺年需求2-氰基吡嗪600t/a,而其设计能力仅为300t/a,年进口量为480t.国内近几年对2-氰基吡嗪的合成研究较多.文章还对我国2-氰基吡嗪的发展提出了建议.     

2-甲基吡嗪研究进展

介绍了2-甲基吡嗪的物性、合成方法及其在医药、化工等领域的应用。     

In Situ Synthesis of the Ammonium Salt of 12-Molybdophosphoric Acid on Niobium Phosphate by Salt-Surface Interaction: The Ammoxidation Functionality of the Catalyst in the Transformation of 2-Methylpyrazine to 2-Cyanopyrazine

The ammonium salt of 12-molybdophosphoric acid (AMPA) has been synthesized, in situ, on niobium phosphate by interacting the phosphate of the support with the molybdenum of the salt. The formation of AMPA, with the popular Keggin structure, is confirmed by X-ray Diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy. The in situ synthesized catalysts exhibited higher ammoxidation activity than the bulk AMPA, showing optimum conversion at 10 wt% Mo loading. The selectivity to nitrile increased with increasing loading.     

A Comparison of Structure and Catalytic Functionality of 12-Molybdophosphoric Acid and Its Ammonium Salt in the Ammoxidation of 2-Methylpyrazine to 2-Cyanopyrazine

Two series of catalysts have been prepared by calcination of 12-molybdophosphoric acid or its ammonium salt at various temperatures, in the region of 300–500 °C. The catalysts have been characterized by nitrogen adsorption, XRD, FTIR spectroscopy and TG/DTA analysis to delineate changes in the solid phase associated with high-temperature treatment. Ammoxidation of 2-methylpyrazine has been carried out on these catalysts in a continuous, vapor phase, fixed-bed reactor, in the reaction temperature range of 360–420 °C. The used catalysts have also been subjected to characterization to ascertain the extent of formation of the salt from its decomposition products. The ammonium salt has shown higher activity, selectivity and better stability, when compared with its parent acid, up to a calcination temperature of 450 °C. However, at temperatures higher than the decomposition temperature the activity of the salt decreases considerably, possibly due to the formation of an undesired species mediated by Mo in the reduced state, thus setting a limit to the calcination temperature.     

Heteropoly compounds in ammoxidation of methylpyrazine

Catalytic properties of molybdophosphoric, mixed vanadium molybdophosphoric heteropoly acids H₃+nPMo_12–n V_nO₄₀ (n=0, 1, 2) and their salts Na₇PV₄Mo₈O₄₀ and Na₈HPV₆Mo₆O₄₀ have been studied in methylpyrazine ammoxidation. Partial vanadium substitution for molybdenum in heteropoly acids increases activity and selectivity towards cyanopyrazine. Sodium salts are somewhat less active and selective.     

丙烷氨氧化制丙烯腈工艺以及催化剂研究进展

由于原料丙烯的短缺以及对丙烯腈需求的不断增加,本文提出一种以丙烷为原料的丙烯腈生产路线,并主要介绍了丙烷氨氧化反应的两种工艺和几种有发展前景的催化剂,为丙烯腈生产提供了一条具有经济吸引力的新路线。     

VCrO/SiO2催化剂的制备、表征及催化芳烃氨氧化的活性

以硅胶为载体,用水溶液浸渍法制备了不同质量分数的钒铬复合氧化物催化剂,用BET、XRD、XPS等手段对其进行了表征,发现钒铬形成了Vv-CrⅢ无定形复合氧化物,是催化反应的活性物种,铬的加入及载体硅胶均有利于形成氧化物的无定形相,抑制晶相的生成,从而提高了反应的选择性。硅胶负载的钒铬复合氧化物催化剂对芳烃氨氧化反应表现出较高的催化活性,可使邻二甲苯氨氧化反应高收率得到邻苯二甲酰亚胺,用质量分数为10%的钒铬复合氧化物催化剂在最佳条件下进行小试,收率可达89.1%。     

丙烷氨氧化制丙烯腈催化剂的设计与研究

运用催化剂设计理论,研制了一系列丙烷氨氧化制丙烯的钒-锑系催化剂,并在固定床微型反应器中进行了对比考察。得到较佳的催化剂为VSb_mW_nK_d4O_x(PAC-34),载体为SIAL,其丙烷转化率为63.7%,丙烯腈选择性为43.7%,丙烯腈收率为27.8%,接近国外较好的催化剂水平。本文还研究了助催化剂、反应条件、载体等因素对催化性能的影响。     

甲基吡啶气相氨氧化V系催化剂研究进展

综述了国内外甲基吡啶气相氨氧化制氰基吡啶V系催化剂的研究进展。在甲基吡啶气相氨氧化中,V系催化剂可以以非负载和负载两种形式起作用。负载型V系催化剂因其机械强度、热稳定性和寿命更优异而得到更加广泛的应用和研究。