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以硅铝胶为原料,在无碱金属体系中水热合成了Beta分子筛。研究了硅铝胶的物理化学性能、添加NaOH和不同n(TEAOH)/n(SiO2)等因素对Beta分子筛结晶度、形貌和铝分布的影响。结果表明,以适宜物理化学性能的硅铝胶为原料,可以在低模板剂用量(n(TEAOH)/n(SiO2)=0.10)下合成Beta分子筛。无钠Beta分子筛的形貌规整,铝分布均匀。在苯与乙烯烷基化反应中,与有钠体系合成的分子筛相比,采用无钠Beta分子筛作为催化剂,在较低空速下可得到较高的乙苯选择性。 相似文献
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B. K. Modhera M. Chakraborty P. A. Parikh R. V. Jasra 《Petroleum Science and Technology》2013,31(11):1196-1208
Abstract Nano-crystalline (about 44 nm in size) zeolite beta was hydrothermally synthesized. Effects of reaction temperature, pressure, hydrogen/n-hexane molar ratio, platinum content of the catalyst, and contact time on n-hexane conversion and selectivity to desired branched-paraffins were studied. At conditions affording the highest yields of branched paraffins, the catalyst did not show any sign of deactivation for 20 h onstream. Performance of Pt, Pd, Ni and Pt + Pd impregnated zeolites was compared. It could be concluded that higher conversions and selectivities may be attributable to the size of the crystals of zeolite beta employed. 相似文献
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在小型固定流化床(FFB)装置上,考察了以Y和ZSM-5分子筛作为催化剂,温度、剂/油质量比对二异丙基萘裂化侧链断裂反应的影响。结果表明,二异丙基萘在分子筛催化剂上极易发生侧链断裂反应,生成萘、C1~C4烷基萘、四氢萘、烷基四氢萘和丙烯等低碳烯烃;较少量的二异丙基萘通过脱氢缩合生成菲、芘等三环以上多环芳烃甚至焦炭。由于扩散和吸附性能的影响,二异丙基萘侧链断裂反应与催化剂的孔径有关,并与催化剂B酸量密切相关。在B酸量较少、吸附性能适宜的ZSM-5催化剂上其侧链断裂反应选择性比Y催化剂的高。当反应温度在425~525℃、剂/油质量比在3~8范围,随着反应温度升高,或者剂/油质量比增加,脱氢缩合反应增强,而烷基侧链断裂反应选择性降低。 相似文献
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采用电子衍射、X-射线衍射、高分辨电子显微术、模拟像计算确定β-沸石点阵参数,即β-沸石属于单斜晶系:am=bm=1.74nm,cm=1.43nm,βm=114.5°。首次拍摄到可清楚分辨β-沸石4、5、6、12员环的结构像,像的衬度、各员环分布与模拟像、原子投影相互匹配表明所建立的晶体结构模型是正确的。高分辨电子显微像还直观显示β-沸石晶体生长过程中产生的高密度晶体缺陷,层错、不全位错、孪晶等类型晶体缺陷普遍存在于微晶粒中。 相似文献
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在小型固定流化床(FFB)装置上,以Y与ZSM-5分子筛为催化剂进行八氢菲的催化裂化反应,考察了分子筛类型、反应温度、剂/油质量比对八氢菲裂化反应的影响。结果表明,八氢菲在分子筛催化剂上容易发生环烷环开环反应,生成丙烷、丙烯、丁烷、丁烯、甲基戊烷和环戊烷、环己烷类环烷烃以及苯、C1~C4烷基取代苯等,烷基苯再发生二次反应生成萘、烷基萘、联苯等;少量八氢菲通过脱氢缩合,生成菲、芘等三环以上多环芳烃,甚至焦炭。由于扩散和吸附性能的影响,八氢菲的环烷环开环反应与催化剂的孔径和B酸量有关;其环烷环开环反应选择性,在孔径和B酸量适宜的Y分子筛催化剂上比在ZSM-5催化剂上高。在Y分子筛催化剂上,当温度为450~525℃、剂/油质量比为3~9,随着反应温度的升高,或者剂/油质量比的增加,八氢菲脱氢缩合反应增强,而环烷环开环反应选择性降低。 相似文献
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采用小型固定流化床(ACE)装置考察了反应温度、分子筛催化剂的活性中心数和分子筛类型对正庚烷催化裂解反应产物的影响,并对裂解链引发反应进行了分析。结果表明, 在ZRP分子筛催化剂催化正庚烷裂解反应中,反应温度可以明显改变正庚烷裂解反应的链引发反应的位置和发生程度;提高反应温度,链引发位置从碳链中心位置的C-C键向靠近碳链端位的C-C键移动,导致不同的产物分布;催化剂活性中心数的增加可以提高正庚烷裂解反应的链引发反应发生程度,并倾向于在碳链中心位置C-C键发生;与Y分子筛和Beta分子筛催化剂相比,具有更多较强BrØnsted酸的ZRP分子筛更有利于链引发反应,并倾向于在碳链中心的C-C键发生。 相似文献
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以Hβ和Ce-β为载体,采用等体积浸渍法制备了Pd/Hβ和Pd/Ce-β催化剂(1%,质量分数)。以含5.0%(质量分数)苯酚的水溶液作原料,考察了该催化剂在苯酚水相加氢脱氧(HDO)反应中的催化性能。研究发现,苯酚水相HDO反应中环己酮加氢生成环己醇的反应是速率控制步骤,双环产物主要源于中间产物环己酮与环己醇的烷基化反应。Ce的引入可提高Pd催化剂的HDO活性,促进催化加氢活性,而抑制烷基化反应。 相似文献
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采用小型固定流化床装置考察了二氢菲、八氢菲和全氢菲在分子筛催化剂上的裂化反应产物,并进行了对比分析。结果表明,在 REUSY 分子筛催化剂上,二氢菲主要发生脱氢缩合反应,生成菲、芘等三环以上多环芳烃甚至焦炭,并阻碍了作为溶剂的正庚烷的裂化;八氢菲、全氢菲主要发生环烷环开环反应,八氢菲的环烷环开环反应产物中乙烯、丙烯、丁烯等 C2~C4烃以及烷基苯的氢转移反应产物萘、烷基萘等 C10烃的收率较高,全氢菲的环烷环开环反应产物中环己烷、烷基苯等汽油组分烃的收率较高;另外,较少量的八氢菲、全氢菲通过脱氢缩合生成菲、芘等三环以上多环芳烃甚至焦炭。氢化菲氢化程度越高越容易发生环烷环开环反应,氢化程度越低越容易发生脱氢反应生成三环以上多环芳烃和焦炭,且氢化程度过低还会抑制饱和烃的裂化。 相似文献
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A. K. Aboul-Gheit A. E. Awadallah D. S. El-Desouki N. A. K. Aboul-Gheit 《Petroleum Science and Technology》2013,31(18):2085-2096
Abstract Pt/H-ZSM-5 and Pt/H-MOR catalysts with different Pt contents were prepared via impregnation using H2PtCl6 · 6H2O or via exchange using Pt(NH3)4Cl2, calcination in air at 530°C and reduction in H2 at 500°C. The prepared catalysts were tested for n-pentane hydroisomerization and hydrocracking via bifunctionality at 250–500°C using a micro-catalytic pulse reactor. It is found that the dispersion of Pt-exchanged zeolites is higher than the corresponding Pt-impregnated zeolites at all Pt contents. It is also found that the dispersion of Pt/H-ZSM-5 catalysts either exchanged or impregnated are higher than the corresponding Pt/H-MOR catalysts. Temperature-programmed desorption (TPD) data showed that the impregnated catalysts possess a higher acid sites number than the exchanged catalysts; and that the Pt/H-ZSM-5 catalysts have a higher number of acid sites than do the Pt/H-MOR catalysts, whereas the latter catalysts possess higher strength of acid sites at all Pt contents. The hydroisomerization activities using Pt exchanged catalysts, supported either on H-ZSM-5 or H-MOR, are higher than the impregnated catalysts at almost all Pt contents. It is also concluded that the H-ZSM-5-supported catalysts, either exchanged or impregnated, are more active than the H-MOR supported ones. Hydrocracking is higher using all loaded H-MOR catalysts. 相似文献
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合成甲基叔丁基醚的沸石分子筛催化剂的研究 总被引:7,自引:0,他引:7
对合成甲基叔丁基醚 (MTBE)反应的几种沸石分子筛进行研究 ,认为催化剂的活性主要受催化剂的酸强度及酸中心数影响。催化剂酸性强 ,催化活性虽高 ,但MTBE选择性差 ;而中强酸中心是醚化反应的最佳酸中心。选择性与催化剂的结构和酸强度有关 ;对选择性较好的催化剂改性 ,增加中强酸的酸中心数 ,可以提高其活性。催化剂的使用寿命与催化剂酸性及结构有关。HY型和HUSY型分子筛的活性最高 ,但选择性差 ,寿命最短。而Hβ和HZSM -5分子筛活性较低 ,但选择性好 ,寿命较长。改性后的 β分子筛性能最佳。 相似文献
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Sulfated nickel/Y-zeolite catalyst has been prepared via impregnation technique. The incorporation of the prepared nickel sulfate precursor into the zeolite support structure has been investigated by using different characterization techniques. The activity and selectivity of the prepared sulfated nickel/Y-zeolite catalyst have been studied through cumene conversion reaction using a catalytic flow system operated under atmospheric pressure and at reaction temperature ranging between 300-425°C. The influence of sulfate species on promoting the catalytic activity toward the formation of the various products, mainly the heavy alkylated benzenes, has also been followed. The data obtained indicated that sulfate species play a dual role as a source of higher acidity and oxidizing character exerted from their induction effect on nickel metal and the hydration factor of the sulfuric acid used or the polynucleated sulfate species formed upon calcination. 相似文献
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《Petroleum Science and Technology》2013,31(11-12):1463-1477
Abstract: Sulfated nickel/Y-zeolite catalyst has been prepared via impregnation technique. The incorporation of the prepared nickel sulfate precursor into the zeolite support structure has been investigated by using different characterization techniques. The activity and selectivity of the prepared sulfated nickel/Y-zeolite catalyst have been studied through cumene conversion reaction using a catalytic flow system operated under atmospheric pressure and at reaction temperature ranging between 300–425°C. The influence of sulfate species on promoting the catalytic activity toward the formation of the various products, mainly the heavy alkylated benzenes, has also been followed. The data obtained indicated that sulfate species play a dual role as a source of higher acidity and oxidizing character exerted from their induction effect on nickel metal and the hydration factor of the sulfuric acid used or the polynucleated sulfate species formed upon calcination. 相似文献
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以正硅酸乙酯(TEOS)为硅源,钛酸四丁酯(TBOT)为钛源,有机硅季铵盐为介孔模板剂成功制备出具有较大介孔孔体积和高外比表面积的多孔TS 1沸
石(TS 1 M)。采用XRD、N2吸附 脱附、SEM和TEM等手段对TS 1 M沸石进行了表征。研究了TS 1 M负载Ni催化剂(Ni/TS 1 M)对棕榈酸的加氢脱氧性能。结果表明,在反应温度260℃、H2分压4 MPa、搅拌速率300 r/min的条件下,在Ni/TS 1 M催化剂上棕榈酸主要发生脱羰反应生成主要产物正十五烷,正十五烷选择性高达92%。 相似文献