共查询到20条相似文献,搜索用时 125 毫秒
1.
2.
3.
4.
5.
6.
7.
磷酸硅铝分子筛SAPO是由PO_4、AlO_4和SiO_4三种四面体构成的三维骨架结构微孔型晶体,具有优异择形选择性、离子交换性、酸性可调性和水热稳定性等特殊性能,广泛用于裂解、烷基化、聚合、重整、加氢、脱氢和水合等反应。综述了SAPO系列分子筛在正构烷烃异构化反应中的应用。SAPO作载体比传统载体制得的催化剂活性高;SAPO-11负载的贵金属催化剂有较高的活性和异构选择性;小粒径SAPO系列分子筛负载的高比表面积、高活性、高稳定性和强抗中毒性能的非贵金属催化材料是异构化催化剂的研究热点。展望了SAPO系列分子筛的研究方向及应用前景。 相似文献
8.
9.
10.
11.
利用XRD、SEM、NH3-PTD和吡啶吸附红外光谱等手段对ZSM-35和SAPO-11分子筛的结构和酸性质进行表征和对比,考察两种分子筛对正丁烯异构化制备异丁烯反应的催化性能。结果表明,对于硅铝型ZSM-35分子筛,由于存在较强的B酸中心,在异构化反应过程中,丁烯二聚及裂解等副反应发生多,异丁烯选择性低。而SAPO-11分子筛主要以中等偏弱的B酸中心为主,加上一维十元环孔道结构,在异构化反应中更有利于异丁烯的生成,表现出更高的异丁烯选择性及收率。 相似文献
12.
13.
Hydroisomerization of Long-Chain Alkane Over Pt/SAPO-11
Catalysts Synthesized from Nonaqueous Media 总被引:1,自引:0,他引:1
Zheming Wang Zhijian Tian Fei Teng Guodong Wen Yunpeng Xu Zhusheng Xu Liwu Lin 《Catalysis Letters》2005,103(1-2):109-116
SAPO-11 molecular sieves were synthesized from nonaqueous media. The effects of Si and Al sources as well as solvents on the catalytic performance of SAPO-11 were investigated by the hydroisomerization reaction of n-dodecane. The samples were characterized by XRD, XRF, N2-adsorption, SEM, NH3-TPD, IR-NH3 and 29Si CP MAS NMR. The SAPO-11 samples synthesized with tetraethoxysilane as the Si source showed higher Si incorporation contents than the SAPO molecular sieves prepared with polymeric Si sources (fumed silica and Si colloidal gel). The reaction results showed that Pt/SAPO-11 catalysts synthesized from ethylene glycol and glycerol media with the monomeric Si and Al sources (tetraethoxysilane, aluminum isopropoxide) exhibited higher catalytic activities than those catalysts with the polymeric Si or Al (pseudo-boehmite) sources, due to the larger external surface area and higher acidity of the former ones. Especially, the catalyst synthesized in an ethylene glycol medium possessed the highest catalytic activity. Over this catalyst, 88% conversion of n-dodecane was achieved at a low temperature of 250 °C. 相似文献
14.
SAPO分子筛及其应用 总被引:3,自引:0,他引:3
磷酸硅铝分子筛(SAPO)是由SiO2、AlO2-、PO2 三种四面体单元构成的微孔型晶体,其孔结构可通过改变不同的合成条件及硅含量来控制.由于骨架呈负电性,具有可交换的阳离子,同时呈现出质子酸性,因此SAPO分子筛被广泛用作吸附剂、催化剂和催化剂载体,是一种具有优异择形选择性、热稳定性和湿热稳定性的新型催化材料. 相似文献
15.
磷酸硅铝分子筛(SAPO)是由SiO2、AlO2^-、PO2^+三种四面体单元构成的微孔型晶体,具有从六元环至十二元环的孔道结构,孔径在0.3nm~0.8mm,骨架呈负电性,具有可交换的阳离子,被广泛用作吸附剂、催化剂和催化剂载体,是一种具有优异择形选择性、热稳定性和湿热稳定性的新型催化材料。SAPO分子筛可呈现出由中强酸到强酸的催化性能,几乎可用于所有的烃类反应。 相似文献
16.
Yingxu Wei Dazhi Zhang Lei Xu Fuxiang Chang Yanli He Shuanghe Meng Bao-lian Su Zhongmin Liu 《Catalysis Today》2008,131(1-4):262-269
SAPO-34 and MeAPSO-34s (MeCo, Mn, Fe) molecular sieves have been synthesized and used as catalysts for chloromethane transformation to light olefins. The influences created by metal incorporation are characterized with XRD, XRF, SEM, NMR, TG and H2-TPR. The synthesized MeAPSO-34s have the same CHA topology structure, while metal incorporation gives rise to the increase of unit cell parameter and crystalline particle size. The coexistence of metal species in the synthesis starting gel has effect on the Si substitution into AlPO framework. Co, Mn or Fe incorporation generates a negligible difference on the chemical shift in 31P and 27Al MAS NMR. 29Si MAS NMR study has demonstrated that metal incorporation favors the Si island formation, predicting the stronger acidity. The reducibility of metal species in the synthesized MeAPSO-34s has been investigated by H2-TPR with the comparison of metal-impregnated SAPO-34. Two weight losses in TG analysis from template decomposition in diluted oxygen suggest different chemical location of template molecules in the molecular sieves. For MeAPSO-34, more template removal occurrence at high temperature range indicates stronger template-framework interaction and stronger acidity than SAPO-34 after calcinations. All the SAPO-34 and MeAPSO-34 molecular sieves are very active and selective catalyst for light olefins production. Metal incorporation improves the catalyst life and favors the ethylene and propylene generation. These catalytic properties enhancements are possibly related to the mechanism of chloromethane conversion with deposited coke species as reaction center. 相似文献
17.
制备不同晶粒形貌的ZSM-5分子筛,采用XRD、SEM和NH_3-TPD对合成的分子筛催化剂进行表征,并用于甲苯歧化反应考察其催化性能。结果表明,制备的ZSM-5分子筛具有六角板状、棒状和球状3种晶粒形貌,棒状分子筛暴露较多的(101)晶面,六角板状分子筛暴露较多的(020)晶面,棒状分子筛具有较高的强酸量。在甲苯歧化反应中,ZSM-5分子筛催化剂暴露(101)晶面越多,产物扩散可能性越大,导致甲苯转化率提高,强酸量增加使副反应发生可能性增大,降低二甲苯选择性。 相似文献
18.
19.
20.
以水热合成法及混合研磨法制备含杂原子硼的ZSM-5分子筛,采用XRD、N2吸附-脱附、FT-IR、UV-Vis、11B MAS NMR、NH3-TPD和SEM等方法对其进行表征,在连续流动常压固定床反应器上考察两种方法制备的分子筛对甲醇脱氢制甲醛反应的催化性能并进行对比。结果表明,水热合成法的B-ZSM-5分子筛中的硼原子主要以四配位的形式存在于分子筛骨架中,研磨法制备的B/ZSM-5分子筛的硼原子主要以三配位的形式存在于骨架外。硼原子的存在状态显著影响分子筛的酸性、比表面积、孔道结构和形貌等物化性能,从而影响甲醇脱氢制甲醛的催化性能。在n(Si)∶n(B)=7.5和反应温度550 ℃条件下,水热合成法的B-ZSM-5分子筛对甲醇的转化率为62.97%,甲醛选择性为68.86%。混合研磨法制备的B/ZSM-5分子筛对甲醇的转化率为47.26%,甲醛选择性为57.72%。 相似文献