金属改性SBA-15应用于乙醇水蒸气重整制氢的研究

采用水热法将Ce金属引入SBA-15骨架,合成一系列Ce-SBA-15（Si/Ce=40,20,10）载体,再通过浸渍法制得Co/Ce-SBA-15催化剂.利用XRD、UV-Vis、FT-IR、H₂-TPR、N₂吸附-脱附等手段对催化剂进行表征,并用于乙醇水蒸汽重整制氢反应（ESR）,考察载体骨架中Ce金属对催化剂结构和性能的影响.结果表明,水热法制备可使得Ce离子进入到SBA-15分子筛骨架,合成的载体仍保持SBA-15特有的介孔结构.与Co/SBA-15催化剂相比,基于铈的储放氧功能,Ce的加入提高了活性金属分散度,降低了反应积碳的生成,改善了催化剂稳定性.适量铈与钴的协同作用,提高了钴物种的分散度,降低了钴的烧结程度,催化剂Co/Ce-SBA-15（Si/Ce=20）具有良好的催化活性,乙醇转化率为96.6%,H₂选择性达到75.5%,反应后积碳率仅为5.6%.     

高比表面积双孔SiO2负载钴基催化剂费托合成反应性能研究

载体的结构可以显著影响钴基费托合成催化剂的活性和产物选择性。大孔结构载体可以改善反应物和产物的传质情况,提升CO转化活性和C₅₊产物选择性;高比表面积载体有利于使负载的金属分散,提高催化剂的金属利用效率和稳定性。然而,要获得同时具备高比表面积和大孔结构特征的载体相对困难。本研究采用结构导向水解法,合成了一种比表面积达1103.2 m²/g的介孔(2.9 nm)-大孔(63.8 nm)双孔二氧化硅(BP-SiO₂)载体,研究了其负载钴催化剂的费托合成反应性能。结果表明,相对规整介孔SBA-15分子筛负载的钴催化剂Co/SBA-15,210℃反应时,催化剂Co/BP-SiO₂的CO转化率提高33.3%,CH₄选择性降低30.1%,C₅₊选择性增加到80.0%,稳定性显著增强。     

孔径对锆同构替代的Co/SBA-15催化剂费-托合成催化性能的影响

采用同构替代方法将锆掺杂进入SBA-15中孔分子筛的骨架中,通过控制合成条件合成出了锆硅摩尔比为1/20的具有四种不同孔径(5.7,7.8,11.6,17.6nm)的Zr-SBA-15中孔有序锆同构替代改性分子筛,并在该改性分子筛上负载质量分数为10%的钴制备出用于费-托合成的钴基催化剂.采用氮气吸附-脱附、XRD、H2-TPR、H2-TPD及氧滴定实验、TEM、29Si固体核磁共振光谱(29SiNMR)、XPS等手段对催化剂进行了表征,系统地研究了同构替代锆掺杂SBA-15分子筛孔径大小对钴基催化剂费-托合成催化活性和产物选择性的影响.同时也采用了原位X射线衍射技术考察了载体孔径对催化剂的还原性能的影响,并结合催化剂的X光电子能谱表征结果进一步讨论了孔径对钴-载体相互作用的影响,为孔径对催化剂的活性以及产物选择性的影响作出了合理的解释.研究结果表明:随着孔径增加,SBA-15中孔分子筛的二维六方有序结构逐渐破坏,催化剂的比表面积下降,钴-载体相互作用降低,钴的晶粒直径增大,催化剂的还原性增加,C5+选择性增加,CO转化率先升高后降低,孔径为7.8nm的催化剂具有更好的费-托合成催化活性,这是催化剂比表面积和...     

SBA-15的硅烷化对钴基催化剂费-托合成性能的影响(英文)

以未硅烷化和硅烷化的SBA-15为载体,采用满孔浸渍法制备了钴基费-托合成催化剂,通过元素分析、N_2吸附-脱附、X射线衍射、H_2程序升温还原、H_2程序升温脱附以及氧滴定等手段对催化剂进行了表征.催化剂的费-托合成活性测试在固定床反应器上进行.研究表明,对于SBA-15硅烷化后制备的催化剂,金属钴与载体之间的相互作用降低,氧化钴的还原度增加.随着三甲基氯硅烷用量的增加,三甲基硅基的表面覆盖度增加,钴的晶粒直径增大.硅烷化后的催化剂的高活性归因于高的还原度.而C_(5+)选择性的增加则归因于钴晶粒直径的增大.     

SBA-15的疏水改性及其对钴基催化剂费-托合成催化性能的影响

利用甲硅烷基化作用制得了不同疏水基团(甲基、二甲基和三甲基)改性SBA-15载体,采用等体积浸渍法制备了质量分数为5%的一系列负载型钴催化剂。结合BET、FT-IR、29Si CP MAS NMR、XRD和H2-TPR等表征手段,考察了SBA-15疏水改性对钴基催化剂物相结构、还原行为以及费-托合成催化性能的影响。催化剂在固定床反应器中在p=2.0 MPa,t=200~250℃,H2和CO体积比为2和GHSV=1 000 h-1的条件下进行评价。结果表明,相对于未改性SBA-15负载钴催化剂,疏水基团改性SBA-15负载钴催化剂的还原度增加,CO转化率提高;Co3O4晶粒粒径增大,难还原钴物种减少,CH4选择性降低,C5+烃选择性增加。     

Co/HMS和Co/SiO2催化剂的表征及在费-托合成反应中的催化性能

 HMS介孔分子筛经水热处理得到无定形SiO2,分别以无定形SiO2和HMS为载体,用浸渍法制得了15%Co/SiO2和15%Co/HMS催化剂. 研究表明: 氧化态Co/SiO2和Co/HMS催化剂中的钴物种以Co3O4形式存在,且Co3O4晶粒粒径均较相应催化剂的孔径大,故有部分钴物种存在于催化剂外表面; 氧化态Co/HMS催化剂中的钴物种堵塞孔道较为严重; Co/HMS催化剂中存在较强的金属-载体相互作用,因此Co/HMS催化剂较Co/SiO2催化剂难还原; Co/HMS催化剂还原后具有较高的钴分散度,使其具有优异的费-托合成反应性能.     

In/SBA-15催化剂的一步法制备及其在水介质中Barbier反应中的应用

采用金属In的石蜡溶液浸渍载体, 一步法制备具有介孔结构的In/SBA-15催化剂. 在水介质中苯甲醛与烯丙基溴的Barbier反应中, 发现负载量为w(In)＝13%的In/SBA-15的催化活性显著高于金属In颗粒催化剂, 而选择性相似, 目标产物1-苯基-3-丁烯基-1-醇的得率可达89.2%. In/SBA-15的高活性主要归因于In活性位在SBA-15上的高分散, 以及规整的介孔结构有利于反应物分子的扩散. 同时, 金属In与SBA-15间较强的相互作用也可稳定In活性位, 显示出良好的应用潜力.     

Al2O3助剂对Co/SiC催化剂F-T反应性能的影响

分别采用沉淀法、尿素水解法制备Al₂O₃/SiC复合载体,采用等体积浸渍法制备Co/Al₂O₃-SiC催化剂。结合N₂吸附、XRD、H₂-TPR、XPS等表征手段,研究Al₂O₃助剂对钴基催化剂物相结构、还原行为以及F-T合成性能等的影响。结果表明,氧化铝加入后增强了载体与钴物种之间的相互作用,提高了钴物种的分散度,降低了钴物种的还原度。尿素水解法引入Al₂O₃后,载体与钴物种具有适中的相互作用,表现出较高的反应活性。沉淀法制备的载体负载钴物种后由于较强的金属-载体相互作用,表现出较优的稳定性。     

贵金属钯修饰的钴基介孔催化剂Pd-Co／SBA15的构效关系研究

制备了贵金属钯修饰的钴基介孔催化剂Pd—Co—SBA-15,采用低温液氮吸脱附、X射线粉末衍射、X射线光电子能谱、氢氧滴定和程序升温技术对其进行了表征,考察了钯助剂的加入量对钴基介孔催化剂结构和织构、表面性能及甲烷催化燃烧等方面性能的影响．结果表明,贵金属钯的加入可显著促进氧化钴物种的还原,有利于活性物种的表面富集,使催化剂上钴物种表面浓度由2．80Co／nm^2增加到3．58Co／nm^2,活性比表面积增加6．9m^2／g．适量贵金属钯的加入可使样品在低温下迅速起活且T90％低于350℃;在整个稳定性考察过程中,双组分样品活性没有出现下降,且其甲烷转化率明显高出参比样85％．     

负载于孔道内部的手性酸碱催化不对称Aldol反应

将手性的伯胺-叔胺与B酸组成的酸碱对负载到介孔材料SBA-15孔道的内表面,得到了一种非均相双功能催化剂.该催化剂在催化丙酮和不同醛的aldol反应时得到了中等的活性和对映体选择性,重复使用6次后活性没有明显下降.与以硅胶为载体的催化剂相比,以介孔SBA-15分子筛为载体的催化剂ee值更高,这可能是由于介孔孔道限制效应引起的.     

Cr-free Co-Cu/SBA-15 catalysts for hydrogenation of biomass-derivedα-,β-unsaturated aldehyde to alcohol

Cr-free bi-metallic SBA-15-supported Co–Cu catalysts were examined in the conversion of bio-mass-derived α-, β-unsaturated aldehyde (furfural) to value-added chemical furfuryl alcohol (FOL). Co–Cu/SBA-15 catalysts with a fixed Cu loading of 10 wt% and varying Co loadings (2.5, 5, and 10 wt%) were prepared by the impregnation method. The catalysts were characterized by X-ray dif-fraction, N2 sorption, H2 temperature-programmed reduction, scanning electron microscopy, ener-gy-dispersive X-ray spectroscopy, high-resolution transmission electron microscopy, CO chemi-sorption, and inductively coupled plasma mass spectrometry. The influence of different reaction parameters such as temperature, pressure, catalyst dosage, and furfural concentration on the cata-lyst performance was evaluated. Relative to catalysts supported on amorphous silica, the current SBA-15-supported Co–Cu catalysts displayed higher performance, attaining a furfural conversion of 99% and furfuryl alcohol selectivity of 80%. The catalytic reactions were conducted in a 100-mL autoclave at 170 °C and 2 MPa H2 pressure for 4 h.     

Influence of the pore structure of MCM-41 and SBA-15 silica fibers on atomic layer chemical vapor deposition of cobalt carbonyl

Mesoporous high surface area MCM-41 and SBA-15 type silica materials with fibrous morphology were synthesized and used as support materials for the ALCVD (atomic layer chemical vapor deposition) preparation of Co/MCM-41 and Co/SBA-15 catalysts. Co/MCM-41 and Co/SBA-15 catalysts were prepared by deposition of Co2(CO)8 from the gas phase onto the surfaces of preheated support materials in a fluidized bed reactor. For both silica materials, two different kinds of preparation methods, direct deposition and a pulse deposition method, were used. Pure silica supports as well as supported cobalt catalysts were characterized by various spectroscopic (IR) and analytical (X-ray diffraction, Brunauer-Emmett-Teller, elemental analysis) methods. MCM-41 and SBA-15 fibers showed considerable ability to adsorb Co2(CO)8 from the gas phase. For MCM-41 and SBA-15 silicas, cobalt loadings of 13.7 and 12.1 wt % were obtained using the direct deposition method. The cobalt loadings increased to 23.0 and 20.7 wt % for MCM-41 and SBA-15 silicas, respectively, when the pulse deposition method was used. The reduction behavior of silica-supported cobalt catalysts was found to depend on the catalyst preparation method and on the mesoporous structure of the support material. Almost identical reduction properties of SBA-15-supported catalysts prepared by different deposition methods are explained by the structural properties of the mesoporous support and, in particular, by the chemical structure of the inner surfaces and walls of the mesopores. Pulse O2/H2 chemisorption experiments showed catalytically promising redox properties and surface stability of the prepared MCM-41- and SBA-15-supported cobalt catalysts.     

Co-Ni2P/SBA-15/Cordierite整体式催化剂的制备及其二苯并噻吩加氢脱硫性能

用共浸渍法制备了Co-Ni2P/SBA-15前躯体,将其调制成活性胶后均匀涂覆到预处理后的堇青石载体上,程序升温还原后制备了一系列Co-Ni2P/SBA-15/堇青石整体式催化剂。采用XRD、N2吸脱附和XPS等对催化剂进行了表征,以1 wt%二苯并噻吩(DBT)/十氢萘溶液为模型化合物,在微型固定床反应器上对催化剂的加氢脱硫(HDS)性能进行了评价。结果表明,不同Co含量的Co-Ni2P/SBA-15/堇青石整体式催化剂中都形成了Ni2P相。Co的加入提高Ni2P/SBA-15/堇青石催化剂的比表面积和孔体积。Co含量为0.55wt%的Co-Ni2P/SBA-15/堇青石整体式催化剂有最好的二苯并噻吩加氢脱硫活性,在380℃,二苯并噻吩转化率能够达到98.8%。Co的加入能够提高二苯并噻吩直接加氢脱硫产物联苯的选择性。     

在超临界正己烷介质中的F-T合成反应行为

在固定床反应器中,以正己烷为超临界介质,研究了三种Co催化剂（浸渍、喷雾干燥、双模催化剂）上的F-T合成反应行为。在相同的Co质量分数下,喷雾干燥催化剂和双模催化剂的活性接近,都高于浸渍催化剂。在喷雾干燥催化剂上CO的转化率显著高于浸渍催化剂。喷雾干燥催化剂F-T产物中具有高的低碳选择性和低的1-烯烃质量分数,然而在相近的CO转化率下,喷雾干燥和浸渍催化剂具有类似的1-烯烃质量分数。对于浸渍催化剂,当Co质量分数从5％增加到15％,CO转化率从8.3％增加到43.6％。含Co5％的催化剂比质量分数为10％、15％、20％催化剂的甲烷选择性低2.0%～3.0%,但产物中1-烯烃的质量分数明显要高。     

Effect of MgO promoter on Ni-based SBA-15 catalysts for combined steam and carbon dioxide reforming of methane

A series of Ni/SBA-15 catalysts with Ni contents ranging from 5 wt% to 15 wt%, as well as another series of 10%Ni/MgO/SBA-15 catalysts, in which the range of the MgO content was from 1 wt% to 7 wt%, were prepared, and their catalytic performances for the reaction of combined steam and carbon dioxide reforming of methane were investigated in a continuous flow microreactor. The structures of the catalysts were characterized using the XRD, H2-TPR and CO2-TPD techniques. The results indicated that the CO selectivity for this reaction was very close to 100%, and the H2/CO ratio of the product gas could be controlled by changing the H2O/CO2 molar ratio of the feed gas. The simultaneous and plentiful existing of steam and CO2 had a significant influence on the catalytic performance of the 10%Ni/SBA-15 catalyst without modification. After reacting at 850 °C for 120 h over this catalyst, the CH4 conversion dropped from 98% to 85%, and the CO2 conversion decreased from 86% to 53%. However, the 10%Ni/3%MgO/SBA-15 catalyst exhibited a much better catalytic performance, and after reacting for 620 h, the CO2 conversion over this catalyst dropped from 92% to around 77%, while the CH4 conversion was not decreased. Oxidation of the Ni0 species as well as carbon deposition during the reaction were the main reasons for the deactivation of the catalyst without modification. On the other hand, modification by the MgO promoter improved the dispersion of the Ni0 species, and enhanced the CO2 adsorption affinity which in turn depressed the occurring of carbon deposition, and thus retarded the deactivation process.     

高效甲醇水蒸气重整制氢的SBA-15改性的Cu/ZnO/Al2O3催化剂

以介孔SBA-15为结构助剂, 制备出用于甲醇水蒸气重整制氢的新型高效氧化硅掺杂的Cu/ZnO/Al₂O₃催化剂, 并与传统Cu/ZnO/Al₂O₃催化剂在相同条件下的催化性能进行了比较. 结果表明, 添加适量介孔SBA-15可显著提高催化剂的催化活性和选择性, 在大幅度提高甲醇转化率的同时有效降低了重整产气中CO的含量. 原位XRD分析证实适量介孔SBA-15的添加对传统Cu/ZnO/Al₂O₃催化剂的微结构性质可产生重要的调控作用, 从而大大改善其催化活性和制氢选择性.     

原位还原法制备Ag/SBA-15及其对CO的催化氧化

以原位还原的方法一步合成了Ag/SBA-15复合催化剂,通过粉末XRD、TEM、ICP-AES和低温氮气吸附-脱附等手段对样品进行了表征.考察了不同催化剂对CO催化活性的影响,结果表明当金属纳米的尺寸大小为6~8nm左右,银的含量为6.86%时(Ag/SBA-15-3)的催化活性最高,在120℃时就可使CO完全氧化,可以重复使用,在100%的转化温度时保持200min转化率仍不降低.     

SBA-15介孔分子筛负载型过渡金属催化燃烧脱除乙腈废气

制备了具有规则孔道结构和较高比表面积的SBA-15介孔分子筛,采用真空旋转蒸发法将过渡金属(Cu,Co,Cr和Mn)负载到SBA-15表面,得到负载型过渡金属催化剂,并将其用于含氰废气催化燃烧的实验中,考察了其催化活性.催化剂的理化性能通过X射线衍射(XRD)、氮气吸附-脱附、透射电子显微镜(TEM)、H2-程序升温还...     

Metallic nickel supported on mesoporous silica as catalyst for hydrodeoxygenation: effect of pore size and structure

Catalytic hydrodeoxygenation (HDO) of anisole, a methoxy-rich lignin-derived bio-oil model compound, was carried out over a series of Ni-containing (5, 10, 20, and 30 wt%) catalysts with commercial silica and ordered mesoporous silica SBA-15 as support. Both supports and catalysts were characterized by N₂ adsorption–desorption isotherms, X-ray diffraction, CO chemisorption, and transmission electron microscopy (TEM). Catalytic reaction was performed at 250 °C and 10 bar H₂ pressure. Depending on the catalyst support used and the content of active metal, the catalytic activity and product distribution changed drastically. Increase of the nickel loading resulted in increased anisole conversion and C₆ hydrocarbon (benzene and cyclohexane) yield. However, loading more Ni than 20 wt% resulted in a decrease of both conversion and C₆ yield due to agglomeration of Ni particles. In addition, Ni/SBA-15 samples exhibited much stronger catalytic activity and selectivity toward C₆ hydrocarbon products compared with Ni/silica catalysts. The differences in catalytic activity among these catalysts can be attributed to the effect of the pore size and pore structure of mesoporous SBA-15. SBA-15 can accommodate more Ni species inside channels than conventional silica due to its high pore volume with uniform pore structure, leading to high HDO catalytic activity.