Ni-Mo双金属催化剂的甲烷化性能与耐硫稳定性

采用沉淀-浸渍法合成一系列Ni-Mo基双金属催化剂,在固定床反应器中对其催化活性和耐硫性能进行评价,并辅以不同的表征手段阐释其作用机理。实验结果表明,以MCM-41分子筛为载体的催化剂活性和稳定性优于以Na Y、γ-Al_2O_3和拟薄水铝石(PB)为载体的催化剂;反应前后催化剂的表征结果则说明Ni-Mo分子间适宜的相互作用是决定催化剂性能的关键。MCM-41载体催化剂中适宜的Ni-Mo分子间相互作用使得此催化剂中活性组分与载体间的相互作用适中,还原后的活性金属Ni能够均匀分散在载体表面,从而提高了催化剂的耐硫稳定性和抗积炭能力。不同Ni-Mo比同样会影响Ni-Mo分子间的相互作用,通过考察确定20Ni-10Mo/MCM-41的活性和稳定性最优。     

Pd-β/MCM-41复合分子筛加氢裂解废食用油性能研究

以碱处理β沸石作为硅铝源,以CTAB为模板剂,合成了β/MCM-41介孔-微孔复合分子筛,以其为载体制备Pd-β/MCM-41复合分子筛催化剂,利用XRD、N₂吸附-脱附、NH₃-TPD和XRF等技术对其进行了表征,并与γ-Al₂O₃、USY、ZSM-5等载体制备的催化剂比较了废食用油加氢裂解活性。结果表明：β/MCM-41复合分子筛同时具备β沸石和MCM-41分子筛的结构,β/MCM-41为载体时,Pd-β/MCM-41催化剂具有适宜的中强酸性中心,适宜的孔道分布结构,催化剂加氢裂解废食用油的活性最高。此外还考察了催化剂制备条件对废食用油加氢裂解反应的影响,结果表明：采用离子交换法制备负载量2%的Pd-β/MCM-41复合分子筛催化剂、焙烧温度为500 ℃时,催化剂对废食用油加氢裂解的效果最好。此时,原料油的转化率可以达到85.9%,生物汽油的收率可以达到16.4%,生物柴油的收率达到17.8%,且此催化剂水热稳定性较好,再生性能良好,工业化应用前景较好。     

不同负载方式Fe/改性MCM-41催化剂的制备及其降解亚甲基蓝性能研究

以自制二元共聚物聚[苯乙烯—3-（甲基丙烯酰氧）丙基三甲氧基硅烷]改性MCM-41,并以其为载体分别采用浸渍负载活性金属、原位负载活性金属和NaBH₄还原负载活性金属的方式制备铁基异相催化剂。研究了3类催化剂降解亚甲基蓝的性能差异。结果显示,在3种催化剂中,浸渍负载活性金属制备的催化剂具有最好的催化活性,25 min时亚甲基蓝去除率为81.2%。同时采用XRD、TEM、FTIR、XPS、压汞测试等手段分析了催化剂具有优异性能的原因。表征结果表明:Fe与改性MCM-41间的相互作用及催化剂孔结构,两者的协同作用是催化剂具有优异性能的原因。     

MCM-41负载Pt-Al催化剂的制备及其表征

以介孔硅MCM-41为载体、无水乙醇为溶剂、氯化铝为促进剂,采用浸渍法制备了Pt-Al/MCM-41催化剂。利用XRD、XPS、TEM、FTIR、N₂吸附-脱附、NH₃-TPD对催化剂进行了表征,重点讨论了不同Pt-Al负载顺序对催化剂结构和性能的影响,并将其应用于硅氢加成反应。结果表明,Pt和Al的负载顺序不同会影响催化剂的有序度、Pt颗粒的分散程度和酸性,其中,Pt-Al/MCM-41催化剂的有序度和Pt颗粒的分散程度相对最好,酸性相对较强。在七甲基三硅氧烷与烯丙醇聚氧乙烯醚的硅氢加成反应中,不同催化剂对七甲基三硅氧烷的转化率影响顺序为Pt-Al/MCM-41 > Pt+Al/MCM-41 > Al-Pt/MCM-41 > Pt/MCM-41。     

低温选择加氢脱硫醚催化剂NiMoZn/Al2O3中Zn的作用

以Al₂O₃作为载体,采用等体积浸渍法制备了多种不同的金属氧化物催化剂,考察其低温选择加氢脱硫醚活性。以1-戊烯和叔丁基甲基硫醚的环己烷模型化合物为反应原料,考察助剂的添加对NiMo/Al₂O₃催化剂性能的影响,并筛选出选择加氢脱硫活性最优的催化剂;接着以FCC全馏分汽油进行150h的长周期实验考察最优催化剂的性能;通过SEM、XRD、H₂-TPR、C₄H₄S-TPD、硫碳分析对催化剂进行了表征。实验结果表明:经过适当组合的三组分催化剂的选择加氢脱硫醚的性能有所改变,其中以NiMoZn/Al₂O₃催化剂的选择加氢脱硫醚性能最好,并在长周期试验中表现出很好的活性和稳定性。表征结果证实Zn的加入起到了分相作用,促进NiO向表面迁移;降低活性组分与载体间的强相互作用,有利于组分的还原;适宜的Zn含量有利于催化剂表面的活性相均匀分布;Zn促进催化剂对硫化物的吸附。     

ZrO2添加对MoO3/Al2O3催化剂耐硫甲烷化性能的影响

采用共沉淀法制备了ZrO₂-Al₂O₃复合载体,并进一步制备了MoO₃/ZrO₂-Al₂O₃催化剂,考察了不同ZrO₂质量分数对催化剂结构及其耐硫甲烷化性能的影响。利用N₂物理吸附、X射线衍射、H₂程序升温还原和透射电子显微镜等手段对催化剂的结构进行了表征。结果表明,MoO₃/ZrO₂-Al₂O₃中ZrO₂的添加可以明显削弱MoO₃与载体间的相互作用,促进Mo物种的还原,适量ZrO₂的存在还有助于提高催化剂的比表面积,改善Mo活性相的分散性,使催化剂表现出优异的耐硫甲烷化活性。     

分子筛-氧化铝基FCC汽油异构/加氢脱硫催化剂研究

采用等体积浸渍法分别制备了以SAPO-11/γ-Al 2O3,Hβ/γ-Al2O3,HY/γ-Al2 O3,MCM-41/γ-Al2O3复合物为载体的负载型Co-Mo催化剂,采用BET、NH3-TPD、FT-IR等技术表征了催化剂载体.在固定床反应装置上,以噻吩和1-己烯分别作为加氢脱硫和烯烃异构反应的探针分子,考察了催化剂的异构化性能和加氢脱硫性能,研究了复合载体MCM-41/γ-Al2O3配比及其磷酸(P)和柠檬酸(CA)改性对催化剂催化性能的影响.结果表明,MCM-41:γ-Al2 O3质量比为7:3的复合物是适宜的催化剂载体;P或CA改性增加了载体的B酸中心和L酸中心以及AB/AL比值;载体P或CA改性皆对催化剂的加氢脱硫性能有明显的促进作用,而未能明显改善催化剂的异构性能.     

Co掺杂对Ce/MCM-41和Ce/SBA-15催化剂催化氧化甲苯性能的影响

以分子筛为载体,采用等体积浸渍法制备Ce/SBA-15、Ce/MCM-41、Ce Co/SBA-15和Ce Co/MCM-41催化剂。用N2吸附-脱附、X射线衍射、扫描电子显微镜、H2程序升温还原、X射线光电子能谱和傅立叶变换红外光谱等对载体和催化剂进行表征,并考察催化剂催化氧化甲苯的活性。结果表明,与载体相比,随着Ce和Co的浸渍,催化剂的比表面积和孔容下降,但仍然保持了载体的有序介孔结构。引入的Ce和Co没有进入分子筛骨架,而是以立方相固溶体形式存在于分子筛表面和孔道中。催化剂催化氧化甲苯活性顺序依次为:Ce Co/SBA-15>Ce Co/MCM-41>Ce/MCM-41>Ce/SBA-15。共浸渍Ce和Co的催化剂活性明显优于只浸渍Ce的催化剂,活性与其还原性能直接相关,Ce Co/SBA-15催化剂具有最低的还原温度和最好的供氧能力,从而表现出最优的催化性能。     

SO2-4/ZrO2/MCM-41催化合成柠檬酸三丁酯的研究

水热合成了介孔材料MCM-41,并以其为载体负载固体超强酸SO^2-₄/ZrO₂,通过XRD和N2吸附/脱附对制备的SO^2-₄/ZrO₂/MCM-41催化剂进行表征,认为MCM-41负载SO^2-₄/ZrO₂后,仍为长程有序的六方孔道结构。在固定床反应器中,以柠檬酸和正丁醇为原料,研究该催化剂合成柠檬酸三丁酯的活性。对反应条件进行了考察,得出最佳反应条件：温度140 ℃,空速1.0 h^-1,醇酸物质的量比为4.5。在此条件下,柠檬酸的酯化率最高可达94.5％。48 h的寿命实验结果表明,该催化剂具有较好的稳定性。     

CoPc/MCM-41催化氧化环己烯合成环己烯酮

以MCM-41型介孔分子筛为载体,酞菁类金属大环配合物为活性组分合成出了CoPc/MCM-41型催化剂,并对其结构进行了表征。红外、XRD和热重分析证实,催化剂活性组分负载后其热稳定性明显增加。进而以自制的CoPc/MCM-41为催化剂,对分子氧氧化环己烯制备环己烯酮的工艺条件进行了探索,结果表明,在催化剂用量120 mg(5 mL环己烯),反应温度55℃,反应时间8 h,二氯乙烷为溶剂的条件下,环己烯酮的单程产率可达24.2%,催化剂可分离回收,回收催化剂重复使用5次后,活性下降约3%。     

Ni and Mo interaction with Al-containing MCM-41 support and its effect on the catalytic behavior in DBT hydrodesulfurization

A series of Mo and NiMo catalysts supported on Al-containing MCM-41 was prepared and characterized by N₂ physisorption, XRD, ammonia TPD, temperature programmed reduction (TPR), UV-Vis diffuse reflectance spectroscopy (DRS) and ²⁷Al MAS-NMR. It was shown that the incorporation of Al atoms into the siliceous MCM-41 framework causes a deterioration of the textural characteristics and some loss in the periodicity of the MCM-41 pore structure. However, the acidity of the Al-containing MCM-41 is substantially higher. The dispersion of Mo and Ni oxidic species increases with the incorporation of aluminum in the MCM-41 support due to the strong interaction of Mo and Ni oxidic species with aluminum atoms of the support. However, the strong interaction of metal species with the Al-containing MCM-41 supports, up to the formation of Al₂(MoO₄)₃ in the case of unpromoted Mo catalysts, produces an increase in the proportion of Ni and Mo species difficult to reduce. When Ni and Mo are impregnated simultaneously the formation of Al₂(MoO₄)₃ is prevented because of the competitive interaction of both, Ni and Mo species, with Al atoms of the support. For both, Mo and NiMo catalysts, maximum catalytic activity in dibenzothiophene (DBT) hydrodesulfurization is observed for the catalysts supported on Al-MCM-41 with SiO₂/Al₂O₃ molar ratio of 30. When Al-containing MCM-41 is used as a support for NiMo catalyst, some cracking of the main reaction products (biphenyl (BiP), cyclohexylbenzene (CHB) and dicyclohexyl (DCH)) is observed.     

甲醇羰基化双组分催化剂表征研究

采用浸渍法制备了Ni/AC单组分催化剂和Ni-Mo/AC双组分催化剂,用固定床催化反应器评价了催化剂性能,实验证明Ni-Mo/AC可使甲醇的转化率达到93.86%,羰化产物收率达到62.71%。通过XRD、XPS、BET等手段对催化剂进行了表征。结果表明,少量Mo的加入,改变了Ni的表面状态以及Ni与活性炭之间的相互作用,Mo与Ni相互作用形成催化活性中心。Mo主要作为结构型助剂,可使NiO易于还原,增加了羰化活性中心数量,提高了催化剂的活性。     

重芳烃轻质化催化剂n（Ni）/n（Ni+Mo）的优化与分析

以β分子筛为载体,在保持金属总负载量不变的情况下,采用等体积浸渍法制备了4种不同n（Ni）/n（Ni+Mo）的催化剂。分别采用X射线衍射（XRD）、比表面积测试（BET）、氨程序升温脱附（NH₃-TPD）、氢程序升温还原（H₂-TPR）、氢程序升温脱附（H₂-TPD）和热重-差热分析（TG-DTG）等方法对催化剂进行了表征。结果表明,4种催化剂的酸量和酸强度相近,在n（Ni）/n（Ni+Mo）等于基准+0.2时,Mo与载体之间的相互作用最弱,其氢气吸附量最多且积炭量最少;采用某炼厂重整C₁₀⁺ 重芳烃对4种催化剂进行评价,结果表明n（Ni）/n（Ni+Mo）等于基准+0.2催化剂具有最优的催化活性和稳定性。上述结果表明,影响重芳烃轻质化催化剂活性和稳定性的关键因素是催化剂氢气吸附量的多少,氢气吸附量越多金属表面的溢流氢效应越明显,积炭前驱体被溢流氢及时消除,从而保护了催化剂的加氢活性中心不被积炭覆盖,有助于催化剂在较高活性下保持稳定。     

合成四氢噻吩非负载Ni-Mo催化剂的制备与表征

采用溶胶-凝胶法制备了非负载Ni-Mo复合氧化物催化剂,采用N2吸附-脱附、X射线衍射(XRD)、红外光谱(FT-IR)、X射线能谱(EDS)和H_2程序升温还原(H_2-TPR)等手段对催化剂进行了表征。在连续流动固定床反应器上,以环丁砜体积分数为10%的乙基苯溶液为原料加氢脱氧合成四氢噻吩为探针反应,考察了不同Mo和Ni的物质的量之比对含硫氧化合物选择性加氢脱氧性能的影响。结果表明:采用溶胶-凝胶法可制备较高比表面积催化剂,活性组分Ni和Mo发生相互作用形成了复合氧化物Ni MoO_4;随着Mo和Ni的物质的量之比的增大,催化剂表面的活性组分Mo的含量先增大后减小,在Mo和Ni的物质的量之比为0.6时,催化剂表面的Mo含量最高,其催化性能较好,该催化剂在230℃,0.3 MPa和液时空速为1 h-1的条件下,环丁砜转化率为91.3%,四氢噻吩选择性为84.1%。     

Effects of small MoO3 additions on the properties of nickel catalysts for the steam reforming of hydrocarbons III. Reduction of Ni-Mo/Al2O3 catalysts

Ni/Al₂O₃ catalyst modified by small amounts of Mo show unusual properties in the steam reforming of hydrocarbons. There are no data about the effect of small amounts of molybdenum on reduction of the Ni-Mo supported catalysts. The properties of these very complex systems depend on the conditions of successive preparation stages (calcination, reduction) or the process conditions.

A series of Ni/Al₂O₃ catalysts modified by Mo were prepared in order to investigate the influence of promoter amounts and preparation sequence on their properties. Temperature programmed reduction (TPR) has been employed to study the reducibility of Ni-Mo/Al₂O₃ catalysts. Catalysts were further characterized by BET area, H₂ chemisorption and X-ray diffraction measurements.

The TPR curves of Ni-Mo/Al₂O₃ catalysts are very complex. Mo addition leads to the decrease of catalysts reducibility. However, complete reduction of NiO and MoO₃ can be achieved at 800 °C. The reduction course depends on the sequence of nickel and molybdenum addition into the support. Precise measurements of Ni peaks positions in the XRD pattern of Ni/Al₂O₃ and Ni-Mo/Al₂O₃ samples show the possibility of Ni-Mo solid solution formation.     

基于MCM-41的镍基甲烷化催化剂活性与稳定性

采用浸渍法分别以MCM-41,Al₂O₃和SiO₂ 为载体制备了不同镍负载量的甲烷化催化剂,并在连续流动固定床反应装置上对其甲烷化催化活性进行了评价。研究结果表明,与Ni/Al₂O₃和Ni/SiO₂相比,相同镍负载量的Ni/MCM-41催化剂具有更好的催化活性。同时研究了Ni含量对于Ni/MCM-41催化剂催化活性的影响,发现随着Ni含量的增加,CO转化率和CH₄收率逐渐升高,并且在Ni含量大于10%（质量分数）以后趋于稳定。在n（H₂）：n（CO）=3：1、反应压力1.5 MPa、反应温度350℃及质量空速12000 ml·h^-1·g^-1的反应条件下,10%Ni/MCM-41催化剂CH₄选择性达到94.9%,CO转化率接近100%。在100 h催化活性稳定性试验中,10%Ni/MCM-41催化活性无明显下降,表现出良好的催化活性稳定性。采用X射线衍射（XRD）、氮气物理吸附（BET）、热重分析（TG）及氢气程序升温还原（H₂-TPR）等技术手段对催化剂进行了表征,结果表明Ni颗粒大小是影响Ni/MCM-41催化剂催化活性的主要因素。     

A simple method to prepare highly active and dispersed Ni/MCM-41 catalysts by co-impregnation

A simple method for preparing highly active and dispersed supported metal catalysts was developed by co-impregnation. Compared with conventional wetness impregnation, addition of moderate ethylene glycol into the metal nitrate aqueous solution could enhance interaction with MCM-41 surface, resulting in formation of very small NiO particle size (3.5 nm) and high dispersion of the active phase. The Ni/MCM-41 catalysts using co-impregnation exhibited excellent catalytic performance for low temperature hydrogenation of naphthalene with 100% conversion at 55 °C, which could rival the activity of commercial Raney Ni catalyst. The obtained catalysts were characterized by XRD, TEM, TG-DSC, FT-IR, BET and TPR.     

Methane reforming reaction with carbon dioxide over SBA-15 supported Ni-Mo bimetallic catalysts

A series of mesoporous molecular sieves SBA-15 supported Ni-Mo bimetallic catalysts (xMo1Ni, Ni = 12 wt.%, Mo/Ni atomic ratio = x, x = 0, 0.3, 0.5, 0.7) were prepared using co-impregnation method for carbon dioxide reforming of methane. The catalytic performance of these catalysts was investigated at 800 °C, atmospheric pressure, GHSV of 4000 ml·g_cat^− 1·h^− 1 and a V(CH₄)/(CO₂) ratio of 1 without dilute gas. The result indicated that the Ni-Mo bimetallic catalysts had a little lower initial activity compared with Ni monometallic catalyst, but it kept very stable performance under the reaction conditions. In addition, the Ni-Mo bimetallic catalyst with Mo/Ni atomic ratio of 0.5 showed high activity, superior stability and the lowest carbon deposition rate (0.00073g_c·g_cat^− 1·h^− 1) in 600-h time on stream. The catalysts were characterized by power X-ray diffraction, N₂-physisorption, H₂-TPR, CO₂-TPD, TG and TEM. The results indicate that the Ni-Mo bimetallic catalysts have smaller metal particle, higher metal dispersion, stronger basicity, metal-support interaction and Mo₂C species. It is concluded that Mo species in the Ni-Mo bimetallic catalysts play important roles in reducing effectively the amount of carbon deposition, especially the amount of shell-like carbon deposition.     

载体结构对钙钛矿氨分解催化活性的影响

采用溶胶凝胶法,制备了负载型镍基钙钛矿型催化剂,并在常压微反应装置上对其氨分解催化活性进行了评价。采用BET、XRD、TPR、TEM等方法对催化剂进行表征。研究结果表明,以MCM-41分子筛为载体的催化剂,由于其较大的比表面积和规整的介孔结构,使活性组分能够很好地分散在载体表面,有利于增加有效活性位,提高活性组分的反应能力,表现出很好的氨分解催化活性。以NiO计,负载量为20%的LaNiO₃/MCM-41具有比非负载的LaNiO₃更好的催化活性,这样不仅提高了催化活性,还大大地减少了活性组分用量,降低了生产成本,从而具有很好的应用前景。