Synthesis of polyoxymethylene dimethyl ethers over zeolite catalysts
-
摘要: 以甲醇、甲缩醛和三聚甲醛为原料,考察了分子筛孔道结构、晶粒粒径、酸性及反应体系对合成聚甲氧基二甲醚反应性能的影响,并筛选出最佳反应条件。结果表明,HMCM-22分子筛具有良好的催化性能。在最佳反应条件下,以甲醇与三聚甲醛为原料,DMM2~8的选择性为65.1%;而以甲缩醛和三聚甲醛为原料,DMM2~8的选择性则达到90.6%。NH3-TPD结果表明,弱酸位有利于三聚甲醛解聚为甲醛,中强酸位促进长链分子生成,而强酸位导致DMM为主要产物。Abstract: Synthesis of polyoxymethylene dimethyl ethers was carried out on HMCM-22, Al-YNU-1 and MOR zeolites by the condensation of trioxane and methanol or methylal. The crystal structures and surface acidity of the catalysts were characterized by XRD, SEM and NH3-TPD. It was found that DMM2~8 selectivity was influenced by the acid strength and density of zeolites and reaction conditions. HMCM-22 showed much higher selectivity to DMM2~8 than Al-YNU-1 and MOR. Under the optimal conditions, the DMM2~8 selectivity reached 65.1% and 90.6% in ME/TRIox and DMM/TRIox systems respectively. It was shown that the moderately strong acid sites were probably responsible for the formation of long chain DMMn, while the strong acid sites werefor DMM.
-
Key words:
- HMCM-22 /
- polyoxymethylene dimethyl ethers /
- methylal /
- methanol /
- trioxane
-
雷艳华, 孙清, 陈兆旭, 沈俭一. 合成聚甲醛二甲基醚反应热力学的理论计算[J]. 化学学报, 2009, 67(8): 767-772. (LEI Yan-hua, SUN Qing, CHEN Zhao-xu, SHEN Jian-yi. Theoretical calculations on the thermodynamics for the synthesis reactions of polyoxymethylene dimethyl ethers[J]. Acta Chimica Sinica, 2009, 67(8): 767-772.) ARVIDSON M, FAKLEY M E, SPENCER M S. Lithium halide-assisted formation of polyoxymethylene dimethyl ethers from dimethoxymethane and formaldehyde[J]. J Mol Catal, 1987, 41(2): 39l-393. BURGER J, SIEGERT M, STROFER E, HASSE H. Poly(oxymethylene) dimethyl ethers as components of tailored diesel fuel: Properties, synthesis and purification concepts[J]. Fuel, 2010, 89(11): 3315-3319. 赵启, 王辉, 秦张峰, 吴志伟, 武建兵, 樊卫斌, 王建国. 分子筛催化剂上甲醇与三聚甲醛缩合制聚甲氧基二甲醚[J]. 燃料化学学报, 2011, 39(12): 918-923. (ZHAO Qi, WANG Hui, QIN Zhang-feng, WU Zhi-wei, WU Jian-bing, FAN Wei-bin, WANG Jian-guo. Synthesis of polyoxymethylene dimethyl ethers from methanol and trioxymethylene with molecular sieves as catalysts[J]. Journal of Fuel Chemistry and Technology, 2011, 39(12): 918-923.) FLEISCH T H, SILLS R A. Beyond GTL-FT: Large-scale gas conversion through oxygenates[J]. Stud Surf Sci Catal, 2004, 147(1): 31-36. YING W, GEN B L, WEI Z. Study on the application of DME/diesel blends in a diesel engine[J]. Fuel Process Technol, 2008, 89(12): 1272-1280. CHEN J, TANG Z H, XIA C G, ZHANG X Z, LI Z. Method for preparing polymethoxymethylal: US, 7560599[P]. 2009-07-14. SCHELLING H, STROEFER E, PINKOS R, HAUNERT A, TEBBEN G D, HASSE H, BLAGOV S. Method for producing polyoxymethylene dimethyl ethers: CN, 101048357A[P]. 2007-10-03. 陈静, 唐中华, 夏春谷, 张新志, 李臻. 聚甲氧基甲缩醛的制备方法: 中国, 101182367A[P]. 2008-05-21. (CHEN Jing, TANG Zhong-hua, XIA Chun-gu, ZHANG Xin-zhi, LI Zhen. Method for preparing polymethoxymethylal: CN, 101182367A[P]. 2008-05-21.) 高晓晨, 杨为民, 刘志成, 高焕新. HZSM-5分子筛用于合成聚甲醛二甲基醚[J]. 催化学报, 2012, 33(8): 1389-1394. (GAO Xiao-chen, YANG Wei-min, LIU Zhi-cheng, GAO Huan-xin. Catalytic performance of HZSM-5 molecular sieve for synthesis of polyoxymethylene dimethyl ethers[J]. Chinese Journal of Catalysis, 2012, 33(8): 1389-1394.) BURGER J, SIEGERT M, STROFER E, HASSE H. Chemical equilibrium and reaction kinetics of the heterogeneously catalyzed formation of poly(oxymethylene) dimethyl ethers from methylal and trioxane[J]. Ind Eng Chem Res, 2012, 51(39): 12751-12761. FAN W, PENG W, NAMBA S, TATSUMI T. Synthesis and catalytic properties of a new titanosilicate molecular sieve with the structure analogous to MWW-type lamellar precursor[J]. J Catal, 2006, 243(1): 183-191. CORMA A, CORELL C, PEREZ-PARIENTE J. Infrared spectroscopy, thermoprogrammed desorption, and nuclear magnetic resonance study of the acidity, structure, and stability of zeolite MCM-22[J]. Zeolites, 1995, 15(7): 576-582. BRENDAN C, WILLIAM M C, WILLIAM A M. Heteroionic forms of zeolites L and mordenite: A heat of immersion study[J]. J Catal, 1976, 45(2): 332-338. FAN W B, WEI S Q, TOSHIYUKI Y, SATOSHI I, LI J F, WANG J G, TATSUMI T. Synthesis, characterization, and catalytic properties of H-Al-YNU-1 and H-Al-MWW with different Si/Al ratios[J]. J Catal, 2009, 266(2): 268-278. AYRAULT P, DATKA J, LAFORGE S, MARTIN D, GUISNET M. Characterization of the internal and external acidity of H-MCM-22 zeolites[J]. J Phys Chem B, 2004, 108(36): 13755-13763.
点击查看大图
计量
- 文章访问数: 788
- HTML全文浏览量: 21
- PDF下载量: 578
- 被引次数: 0