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硫化态NiW/Al2O3催化剂加氢脱硫活性相的研究Ⅱ.程序升温还原表征 总被引:1,自引:0,他引:1
采用程序升温还原法对一系列具有相同W含量和不同Ni含量的硫化态NiW/Al2O3催化剂进行了表征,以考察催化剂中不同硫物种的数量及还原性能. 结果表明,含有助剂Ni的催化剂TPR谱在673~873 K出现了一个还原峰,归属为催化剂的NiWS混合相被分解生成的硫化镍物的还原. 随着助剂Ni含量的增加,与该还原峰相应的H2S生成量增大,表明形成了更多的NiWS活性相. 另外,Ni/(Ni+W)原子比为0.41的催化剂样品的噻吩加氢脱硫活性随着还原温度的升高而急剧下降,证实了催化剂在还原过程中活性相被逐步分解. 相似文献
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以FeCrAl合金薄片为基底,Al2O3浆料为过渡胶体,不同摩尔比的Cu、Co为催化活性组分,制备了一系列CuxCo1-x/Al2O3/FeCrAl(x=0-1)新型整体式催化剂.采用X射线粉末衍射(XRD),扫描电子显微镜(SEM),X光电子能谱(XPS)和程序升温还原(TPR)等手段对催化剂的结构进行了表征.在微型固定床反应器上评价了催化剂的催化甲苯燃烧性能.研究结果表明:在所制备的整体式催化剂上,当Cu含量比较低时,形成了Cu-Co-O固溶体;当Cu含量比较高时,可以测得CuO的衍射峰.催化剂表面颗粒大小和形貌与Cu、Co摩尔比密切相关.在催化剂表面,Co以Co2+和Co3+价态存在,而Cu主要以Cu2+价态存在.催化剂中的Cu可以改善Co的氧化还原性,从而有利于催化剂活性的提高.在所制备的催化剂中,Cu0.5Co0.5/Al2O3/FeCrAl催化剂具有最好的活性,甲苯在374oC可以完全催化燃烧消除. 相似文献
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通过程序升温还原磷钼酸盐前体的方法制备了无负载磷化钼(MoP)催化剂,并采用XRD,BET,XPS和高压连续微反技术,考察了催化剂的性质,研究了还原温度对催化剂HDN,HDS和HYD性能的影响. 结果表明,在还原温度为600~800 ℃范围内,成功制备出磷化钼催化剂. 高压连续微反结果表明,MoP的催化特性与其比表面积、还原度和表相组成有关,比表面积大、还原度适中和表相Moδ+/Pδ-比适中的磷化钼具有更高的催化活性; 650~700
℃为最合适的还原温度,高于或低于该温度时所制备的MoP催化剂活性均大幅度下降. 在合适的条件下,MoP催化剂对噻吩HDS,吡啶HDN和环己烯HYD的转化率可分别达到94.3%,100.0%和90.3%. 相似文献
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AlMCM-41负载Ni催化剂的正十二烷加氢转化反应性能研究 总被引:2,自引:0,他引:2
采用N_2脱附、XRD,NH_3-TPD和H_2-TPR等手段表征中孔分子筛AlMCM-41负载 Ni催化剂。结果表明,AlMCM-41负载Ni后会导致中孔分子筛骨架部分塌陷,孔道有 序度降低,而且,Ni与载体的相互作用随着载体中铝含量的增加而增强。此外,催 化剂的表面酸性以弱酸和中强酸为主。正十二烷加氢转化反应评价表明,在催化剂 Si/Al比为17.4 ~ 38.7范围内,随着铝含量的减少,氢解副反应加剧,正十烷的 转化率逐渐升高,异构选择率则以先增加后减小的趋势变化,在Si/Al=23.2时达到 最大值。当Si/Al比为17.4时,催化剂的酸/金属功能呈现较好的匹配,正十二烷裂 解产物以C_6为中心呈对称分布且i/n-(C_4~C_9)比例较高。 相似文献
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AlMCM-41负载Ni催化剂的正十二烷加氢转化反应性能研究 总被引:1,自引:0,他引:1
采用N_2脱附、XRD,NH_3-TPD和H_2-TPR等手段表征中孔分子筛AlMCM-41负载 Ni催化剂。结果表明,AlMCM-41负载Ni后会导致中孔分子筛骨架部分塌陷,孔道有 序度降低,而且,Ni与载体的相互作用随着载体中铝含量的增加而增强。此外,催 化剂的表面酸性以弱酸和中强酸为主。正十二烷加氢转化反应评价表明,在催化剂 Si/Al比为17.4 ~ 38.7范围内,随着铝含量的减少,氢解副反应加剧,正十烷的 转化率逐渐升高,异构选择率则以先增加后减小的趋势变化,在Si/Al=23.2时达到 最大值。当Si/Al比为17.4时,催化剂的酸/金属功能呈现较好的匹配,正十二烷裂 解产物以C_6为中心呈对称分布且i/n-(C_4~C_9)比例较高。 相似文献
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应用X射线衍射(XRD)、程序升温还原(TPR)技术对等体积浸渍法制备的Co—Mo/CNT催化剂进行了表征,采用高压微反装置、以二苯并噻吩为模型化合物,对催化剂进行了HDS活性评价,XRD结果表明:260℃条件下处理催化剂,催化剂的表面物种主要是MoO3,表面物种高度分散;500℃焙烧处理的催化剂的表面物种主要是MoO2,同时在Co—Mo/CNT催化体系中出现了CoMoO3和Co2Mo3O03物种的强衍射峰,高温焙烧时催化剂活性组分在碳纳米管的表面容易聚集形成MoO2等晶体,TPR结果表明:在Co-Mo/CNT催化剂中,表面物种的还原温度低于Co—Mo/γ—Al2O3中物种的还原温度,活性评价表明:催化剂的TPR特性和加氢脱硫活性有很好的对应关系,Co—Mo/CNT具有很高的加氢脱硫选择性,并且活性明显高于Co—Mo/γ—Al2O3催化剂。 相似文献
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In this paper, the effect of catalytic support and sulfiding method on the chemical state of supported Co-Mo catalysts is studied by XPS. After sulfidation with in-situ method, the majority of molybdenum in CNT supported CoMo catalyst is transferred to a species with a formal chemical state Mo(Ⅳ) in MoS2 phase, and the rest to Mo(Ⅴ) which consists of Mo coordinated both to O and S, such as MoO2S2^2- and MoO3S^2-. In case of CoMo/γ-Al2O3 catalyst sulfided with in-situ method, a fraction of molybdenum is transferred to formal state Mo(Ⅳ) in the form of MoS2, but there is still a mount of unreduced Mo(VI) phase which is difficult to be sulfided. In CoMo/CNT catalyric system sulfided with ex-situ method, Mo(IV) in the form of MoS2 is detected along with a portion of unreduced Mo(VI) phase, suggesting that not all the Mo phases are reduced and sulfided by ex-situ method. As for CoMo/γ-Al2O3, a portion of molybdenum is sulfided to intermediate reduced state Mo(V) which consists of Mo coordinated both to O and S, such as MoO2S2^2- and MoO3S^2-, in addition, there is still a fraction of unreduced Mo(Ⅵ)phase. XPS analyses results suggest that CNT support facilitates the reduction and sulfidation of active species to a large extent, and that alumina support strongly interacts with active species, hereby producing a fraction of phase which resists complete sulfiding. Catalytic measurements of catalysts in the HDS of dibenzothiophene (DBT) show that CoMo/CNT catalysts are of higher HDS activity and selectivity than CoMo/γ-Al2O3 catalyst, which is in good relation with the sulfiding behavior of the corresponding catalyst. 相似文献
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Hongyan Shang Chenguang Liu Yongqiang Xu Jieshan Qiu Fei Wei 《天然气化学杂志》2006,15(3):203-210
The dispersion of the active phase and loading capacity of the Mo species on carbon nanotube (CNT) was studied by the XRD technique. The reducibility properties of Co-Mo catalysts in the oxide state over CNTs were investigated by TPR, while the sulfided Co-Mo/CNT catalysts were characterized by means of the XRD and LRS techniques. The activity and selectivity with respect to the hydrodesulfurization (HDS) performances on carbon nanotube supported Co-Mo catalysts were evaluated. It was found that the main active molybdenum species in the oxide state MoO3/CNT catalysts were MoO2, but not MoO3, as generally expected. The maximum loading before the formation of the bulk phase was lower than 6% (percent by mass, based on MoO3). TPR studies revealed that the active species in the oxide state Co-Mo/CNT catalysts were reduced more easily at relatively lower temperatures in comparison to those of the Co-Mo/γ-Al2O3 catalysts, indicating that the CNT support promoted or favored the reduction of the active species. The active species of a Co-Mo-0.7/CNT catalyst were more easily reduced than those of the Co-Mo/CNT catalysts with Co/Mo atomic ratios of 0.2, 0.35, and 0.5, respectively, suggesting that the Co/Mo atomic ratio has a great effect on the reducibility of the active species. It was found that the incorporation of cobalt improved the dispersion of the molybdenum species on the support, and a phenomenon of mobilization and re-dispersion had occurred during the sulfurization process, resulting in low valence state Mo3S4 and Co-MoS2.17 active phases. HDS measurements showed that the Co-Mo/CNT catalysts were more active than the Co-Mo/γ-Al2O3 ones for the desulfurization of DBT, and the hydrogenolysis/hydrogenation selectivity of the Co-Mo/CNT catalysts was also much higher than those of the Co-Mo/γ-Al2O3. The Co-Mo/CNT catalyst with a Co/Mo atomic ratio of 0.7 showed the highest activity, whereas the catalyst with a Co/Mo atomic ratio of 0.35 had the highest selectivity. 相似文献
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堇青石负载La-Mn-O复合氧化物催化剂的甲苯催化燃烧性能 总被引:1,自引:0,他引:1
以堇青石蜂窝陶瓷为载体,以La2O3,Mn(NO3)2为基本原料,掺杂一些稀土等非贵重金属元素,采用浸渍法制备了系列负载La-Mn-O复合氧化物催化剂.考察了焙烧温度等对甲苯催化燃烧性能的影响,并对催化剂进行了XRD,TPR表征.结果表明,800 ℃焙烧的LaMn/Cord催化剂具有较高的甲苯催化燃烧性能;Ce取代催化剂中部分La后能改善催化剂的氧化活性,当Ce∶La=1∶1(摩尔比)时催化性能最佳,在260 ℃的反应温度下甲苯转化率达到90%以上. 相似文献
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噻吩在不同负载磷化钨催化剂上的加氢脱硫 总被引:3,自引:0,他引:3
采用程序升温和高纯氢气还原无定型磷钨酸盐与载体γ-Al2O3机械混合物的方法,制备了活性组分为磷化钨、负载量分别为20%、25%、30%和35%的新型磷化钨催化剂,并对其噻吩加氢脱硫反应活性进行考察。实验结果表明,负载磷化钨催化剂的噻吩加氢脱硫率明显高于非负载磷化钨催化剂;不同负载磷化钨催化剂还原反应均为放热反应,且发生还原反应生成活性组分磷化钨的最低温度大于610℃,对于噻吩加氢脱硫反应,WP1活性较高,WP4活性较低,在340℃时分别为85.23%和67.93%,催化剂WP1具有较好的稳定性。 相似文献
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用溶胶-凝胶法制备了Co/S iO2系列的担载型催化剂,采用SBET、TPR、XRD、O2滴定及室温H2、O2、CO和C2H4微量吸附量热等技术进行了研究.结果表明:Co很好分散,S iO2的含量越高,样品的SBET越大;Co是经由Co3 →Co2 →Co0的还原过程;Co/S iO2系列催化剂上,CO、H2、O2和C2H4的初始吸附热数值均比较接近、饱和覆盖度以50Co/50S iO2最高,O2为多层吸附而H2、CO和C2H4为单层吸附,CO为线式吸附并发生歧化反应生成了C和CO2,C2H4吸附解离生成了H2、乙川(C2H3)和C2H6. 相似文献
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以水热处理的纳米HZSM-5为载体,通过螯合剂乙二胺四乙酸(EDTA)改性制备了一种具有较高脱硫活性和稳定性的EDTA-NiMo/HZSM-5催化剂,并用XRD、ICP、FT-IR、27Al MAS NMR、TG-DTA、Py-IR及NH3-TPD对催化剂进行了表征.结果表明,EDTA与载体之间具有较强的相互作用,这种强相互作用减弱了金属活性组分与载体之间的作用力,抑制非活性NiAl2O4、Al2(MoO4)3的形成,有利于活性组分在载体表面的分散,且添加的螯合剂与金属组分镍可以形成稳定的螯合物,在硫化过程中能改变催化剂的硫化顺序,促使有效脱硫活性中心的形成,提高了催化剂的脱硫活性和稳定性. 相似文献