NiY/MCM-41催化剂的制备及催化氧化脱硫研究

采用后合成法制备复合分子筛Y/MCM-41,并以其为载体,用活性组分硝酸镍对其改性,制备Ni-Y/MCM-41催化剂,并利用XRD、BET、N2吸附-脱附对其进行表征。结果表明,复合分子筛同时具有微孔分子筛Y沸石和介孔材料MCM-41分子筛的特征。以硫质量分数为300μg/g的模拟油进行催化氧化脱硫实验,考察了Ni离子的负载量、反应温度、反应时间、催化剂用量、氧化剂用量等工艺条件对脱硫率的影响。结果表明:硝酸镍的负载量为10%,模拟油用量为20 m L,反应温度为70℃,反应时间为80 min,剂油比(催化剂与模拟油的质量比)为1∶70,V(H2O2)/V(油)=0.03时,脱硫率可达86.53%。     

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%。     

环己烷催化氧化制环己酮的MCM-41催化剂研究

以十六烷基三甲基溴化铵为模板剂,正硅酸乙酯为硅源,采用水热合成法制备纯MCM-41分子筛和掺杂不同金属离子的MCM-41分子筛,并采用等体积浸渍法将一定量的金属离子负载在纯MCM-41分子筛内表面上,制备了负载型和掺杂型2类不同的MCM-41分子筛催化剂.分别考察了负载和掺杂的金属种类、金属Cr负载和掺杂量等对环己烷氧化制环己酮中的催化活性和选择性的影响.研究表明:采用掺杂制备的MCM-41分子筛催化剂活性明显高于负载型MCM-41分子筛催化剂;Cr掺杂量增加,虽然环己烷氧化转化率增加,但产物选择性下降;掺杂Cr的MCM-41分子筛催化剂,用于环己烷氧化制环己酮,在Si与Cr摩尔比为50以下、反应温度75℃、H2O2与环己烷摩尔比为1.2的条件下,环己烷的转化率可达60%左右,环己酮和环己醇的总选择性可达94%以上.     

负载型CTAB/MCM-41介孔分子筛的制备及其对溴代反应催化性能的研究

采用水热晶化法,以CTAB为模板剂合成出MCM-41介孔分子筛,后经过220℃低温焙烧4 h,可成功将CTAB固载于MCM-41,并对产物进行了XRD表征。将制备的CTAB/MCM-41催化剂用于1,7-庚二醇的溴代反应,通过对使用不同催化剂条件下反应速率的比较表明:CTAB/MCM-41的催化活性较好于未负载的CTAB。负载型的催化剂经多次使用后活性基本不变,并且能够简化反应后的分离步骤。     

介孔分子筛MCM-41在有机催化中的研究进展

介绍了近几年MCM-41在环氧化、加氢反应、烷基化、酯化等有机反应中的应用。介孔分子筛MCM-41具有较高的比表面和规整的结构,以及表面带有羟基,是催化剂的优良载体。因此,可以将催化剂引入到MCM-41的结构中,从而提高其性能。认为应在介孔分子筛的水热稳定性、研究合成机理、合成方法等方面加强研究,对介孔分子筛在有机化工催化领域中的应用现状及前景进行了分析。     

助剂掺杂对Fe—MCM-41在环己烷氧化反应中催化性能的影响

z以硅酸钠为硅源,十六烷基三甲基溴化铵为模板剂,硝酸铁为金属源,水热法直接合成Fe—MCM-41,再辅以助剂co和cr形成双金属掺杂的介孔材料,采用XRD、N2吸脱附、TG—DTA、FTIR、ICP对材料的结构和物化性质进行表征。以乙腈为溶剂,H2O2为氧化剂,考察所制备的材料对环己烷氧化的催化活性和选择性的影响。结果表明,与Fe—MCM41的催化性能相比,FeCo—MCM41会使环己烷的转化率下降,但环己醇的选择性增加;而FeCr—MCM41会使环己烷的转化率和环己酮的收率增加。     

MCM-41分子筛催化木糖制备糠醛的研究

以MCM-41分子筛为催化剂,在正丁醇与水构成的两相溶剂体系中,将木糖脱水转化为糠醛。考察了两相溶剂体系中正丁醇与水的体积比、反应温度、反应时间以及MCM-41催化剂循环使用次数对木糖转化率和糠醛收率的影响。实验结果表明:在木糖浓度为10%、催化剂用量为50%(以木糖用量计),正丁醇与水体积比率为1:1,反应温度为170℃时,反应4 h后木糖转化率可达到96.8%,而糠醛收率最高可达44.05%。同时,研究表明,在其它反应条件相同的情况下,加入10%(以木糖用量计)的NaCl可显著提高糠醛收率,增幅可达23.1%。     

HZSM-5/MCM-41对小球藻催化热解的影响

以HZSM-5/MCM-41为催化剂,在管式炉内对小球藻进行了催化热解研究。考察了HZSM-5/MCM-41复合催化剂中MCM-41的添加比例对小球藻热解产物影响,并采用GC-MS和元素分析对所制取生物油进行了表征。结果表明:与HZSM-5催化剂相比,90%HZSM-5与10%MCM-41混合后生物油中3,7,11,15-四甲基-2-十六烯的选择性最好。羧酸类和含氮物质分别降低12.85%、43.97%,脂肪烃和芳烃的质量分数之和达到50.34%,且不存在硬脂酰胺和油酸腈等物质。根据元素分析可知,10%的MCM-41的引入使生物油含氧量降低23.52%,O/C原子比明显降低,H/C原子比得到提高,热值达到32.995 MJ·k-1,且油品组成与生物柴油接近。热重实验表明,分子筛催化剂失活主要是由于积炭的产生,HZSM-5/MCM-41具有良好的稳定性。随着催化剂用量的增加,生物油热值增加,同时含水量也增多,HZSM-5/MCM-41与小球藻质量比例为1:5时,生物油产率最高。     

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。     

MgO/MCM-41对二氧化碳的吸/脱附性能的研究

采用等体积浸渍法制备MgO/MCM-41作为吸附剂,通过静态吸附法对其吸附性能进行了测定。结果表明,制得的吸附剂只存在一个碱性位,二氧化碳吸附后主要以碳酸氢盐的形式存在。当MgO的负载量为20%的时候,对二氧化碳的吸附量最大,在30℃条件下,其对二氧化碳的吸附量为46.6 mg/g。     

石蜡氧化改性的发展及应用

介绍了石蜡的氧化改性方法,阐述了国内外石蜡氧化的生产现状和应用情况,指出了中国在石蜡氧化生产中面临的主要问题及今后的研究方向。     

Catalytic reduction of NOx over transition-metal-containing MCM-41

The catalytic properties of Pt, Rh and Co supported on mesoporous molecular sieves with MCM-41-type structure consisting of SiO₂ and Al₂O₃ were studied for the reduction of NO with propene. Pt supported on siliceous MCM-41 was the most active catalyst, however, significant quantities of undesirable N₂O were formed during the reaction. Pt supported on mesoporous Al₂O₃ and Rh supported on both mesoporous oxides showed a lower activity, but an improved selectivity towards N₂ formation. Co supported on MCM-41-type materials had only a low level of activity for the reduction of NO with propene. For Pt supported on MCM-41-type materials only a minor decrease in the activity was observed when water vapor was added into the reactant gas mixture, while on Rh- and Co-containing catalysts the activity strongly decreased. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Comparative Study on the Catalytic Activity of Mn Containing MCM-41 Molecular Sieves for Oxidation of p-Cymene

Mesoporous silica molecular sieves SiMCM-41, AlMCM-41 with Si/Al ratio equal to 158 and MnMCM-41 with Si/Mn ratio equal to 29 were synthesized by hydrothermal method. Manganese oxide impregnated on SiMCM-41 and on AlMCM-41 catalysts were also prepared by wet impregnation method. These catalysts referred as Mn/SiMCM-41 and Mn/AlMCM-41 (158). Both the manganese incorporated and impregnated catalysts structure was elucidated by XRD. Nitrogen adsorption isotherm was used to determine specific surface area, pore volume, and pore size distribution. The thermal stability of the as-synthesized catalyst was studied using TG-DTA. The presence of Mn²⁺ was evident through DR UV–VIS and ESR spectroscopy. Through ESR studies, MnMCM-41 (29) was assigned to have framework Mn(II) sites. Extra-framework manganese species with well-resolved sextet, centered at g = 2.00 had octahedral symmetry was observed in Mn/SiMCM-41 and Mn/AlMCM-41 (158). Mn retained its +2 oxidation state (ESR active) even upon calcination at 550 °C in presence of air. The catalytic activity of the above-mentioned manganese containing MCM-41 catalysts were tested by vapor phase oxidation of p-cymene with CO₂-free air in the temperature range from 200 to 400 °C in steps of 50 °C. The major products were 4-methylacetophenone (4-MAP), 4-isopropyl benzaldehyde (4-IPB), 1,2-epoxyisopropyl benzaldehyde or 1,2-epoxycumenaldehyde (1,2-ECA) and 4-methyl styrene (4-MS). Among the product selectivity, (4-MAP) was found to be higher than that of others. The order of the activity of catalysts followed Mn/SiMCM-41 > Mn/AlMCM-41 (158) > MnMCM-41 (29) > Mn/SiO₂.     

絮凝法制备TiO2/MCM-41复合光催化剂及其性能的研究

以MCM-41分子筛为介孔材料,采用絮凝法制备复合光催化剂,通过XRD对复合光催化剂的晶型结构和形貌进行了表征,以人工合成染料罗丹明B为降解对象,考察絮凝pH、煅烧时间、煅烧温度、光照时间、催化剂投加量对复合光催化剂活性的影响。实验结果表明：在絮凝pH值为4时所得絮凝污泥,经700℃煅烧2h后的复合光催化剂具有最佳的光催化活性,在紫外光下照射浓度为20mg/L的罗丹明B 40min可获得98%以上的降解效果。     

催化剂Au/CeO_2/MCM-41的制备及其活性研究

文章报道了一种新型催化剂Au/CeO2/MCM-41的制备,并对它的比表面积、晶体结构、表面元素价态、储释氧能力及催化活性进行表征。通过催化剂的活性测试,发现催化剂Au/CeO2/MCM-41对CO氧化具有很高的活性,但催化剂对煅烧温度比较敏感,随煅烧温度上升,催化活性下降很快,可能是因为一方面较高的温度煅烧使金纳米颗粒迅速长大,从而活性很快的下降;另一方面高温煅烧使催化剂发生烧结,从而比表面积下降引起活性的降低。     

Catalytic Oxidation of Alkylaromatics over Mesoporous (Cr)MCM-41

Liquid-phase catalytic oxidation of certain alkylaromatics over mesoporous (Cr)MCM-41 molecular sieves in the presence of chlorobenzene and tertiary butylhydroperoxide showed high substrate conversion and excellent product selectivity. The high catalytic activity of the materials is attributed to the complete oxidation of chromium ions to hexavalent chromium and the absence of pentavalent chromium in the mesoporous matrix.     

脱硫催化剂(四羧基酞菁铝键合MCM-41)的制备及催化活性研究

为了降低油品中的含硫化合物,合成了四羧基酞菁铝,然后将其键合在MCM-41的表面,通过红外光谱进行了表征,最后以四羧基酞菁铝键合MCM-41作为脱硫催化剂,测定了它去除乙硫醇的催化活性。结果表面:脱硫催化剂(四羧基酞菁铝键合MCM-41)对乙硫醇的去除率可以达到97.8%,而且反应速率快,持续时间长,具有良好的催化活性。     

双功能硅烷化修饰MCM-41固载Cosalen催化环己烷氧化

采用双功能硅烷化试剂γ-氨丙基甲基二乙氧基硅烷(AMS),对(MCM-41)全硅介孔分子筛一步进行氨基官能团化和甲基疏水性修饰,然后将双水杨醛缩乙二胺合钴(Cosalen)通过氨基的轴向配位固载在修饰后的载体MCM-41上。X射线衍射和N2物理吸附/脱附的结果表明:经过AMS双功能硅烷化修饰以及固载Cosalen后载体的孔道结构保持良好。考察了硅烷试剂用量对硅烷化效率的影响,结果表明:当AMS的加入量为4.00mmol/g时,甲基修饰量达到1.95mmol/g;水和环己烷的静态吸附结果表明硅烷化修饰后,催化剂载体的疏水性明显增强。制得的催化剂应用于环己烷的分子氧氧化反应,130℃反应2h,环己烷转化率达到7.2%,环己醇和环己酮总选择性达到70.5%,较未经AMS修饰的催化剂Cosalen/MCM-41获得的醇酮总选择性提高了13%。     

Selective Oxidation of 4-Tert-butyltoluene to 4-Tert-butylbenzaldehyde Over Co/MCM-41

Selective oxidation of 4-tert-butyltoluene (TBT) to 4-tert-butylbenzaldehyde (TBBZ) and 4-methylacetophenone (MAP) is reported for the first time using aqueous hydrogen peroxide as oxidant and Co/MCM-41 as the catalyst under mild conditions for the first time. Co/MCM-41 presented reasonable selectivity (82%) of TBBZ with a conversion rate of 15% of TBT without any initiator. Under the suitable reaction conditions, Co/MCM-41 also presented reasonable selectivity (58%) of MAP with a conversion rate of 12% of the substrate. The catalysts can be reused once with almost the same activity.