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介孔分子筛吸附性能的热力学和动力学分析

实验以亚甲基蓝作为模型吸附质,探讨了MCM-41介孔分子筛对模型吸附质亚甲基蓝的吸附性能,并对其吸附过程进行了热力学和动力学分析。结果表明,MCM-41介孔分子筛的吸附率高达94%,对亚甲基兰的吸附符合二级吸附动力学,MCM-41对亚甲基兰的吸附行为属于Freundlich等温吸附,整个吸附过程属于放热反应。     

改性MCM-41负载铁基催化剂的制备及其催化降解亚甲基蓝的研究

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,并以其为载体制备铁基非均相催化剂。研究了该催化剂对亚甲基蓝的催化降解性能,同时利用FT-IR、XRD、SEM、NH3-TPD、氮气等温吸附(BET)等手段分析了分子筛改性后对铁基催化性能的影响。结果表明,改性MCM-41负载铁基催化剂具有优异的催化降解亚甲基蓝性能,25 min时去除率达到81.2%,与纯MCM-41负载铁基催化剂相比,性能提高了33.9%。     

氨基改性的MCM-41吸附水溶液中亚甲基蓝的研究

用3-氨丙基三甲氧基硅烷对MCM-41进行改性,得到MCM-41-NH2吸附剂,用X射线衍射(XRD)、氮气吸附脱附、透射电镜(TEM)和红外光谱对其进行表征。并将其用于去除水溶液中亚甲基蓝(MB)的吸附研究,探讨了吸附剂量、溶液p H、温度和接触时间对亚甲基蓝吸附的影响。结果表明,MCM-41-NH2对亚甲基蓝的吸附是一个吸热过程。吸附等温线符合Langmuir等温吸附模型,吸附动力学符合拟二级动力学模型。     

PW/MCM-41光催化性能研究

以浸渍法制备了负载型光催化剂PW/MCM-41,并对催化剂进行了表征,考察了催化剂在光催化模拟染料废水亚甲基蓝(MB)溶液降解反应中的催化活性.实验结果表明:催化剂负载量为30％、催化剂投加质量浓度为3.0g/L、MB溶液的初始质量浓度为10 mg/L、pH=5、光照时间100 min时,对亚甲基蓝降解率可达91％以上...     

MCM-41分子筛的合成

以十六烷基三甲基溴化铵(CTAB)为结构模板剂,正硅酸乙酯(TEOS)为硅源,正庚烷(MSDS)为辅助剂,合成出了MCM-41分子筛,并采用傅立叶变换红外光谱仪(FTIR)对分子筛结构进行了表征。探索了pH值、CTAB用量、MSDS用量、晶化温度和晶化时间对分子筛质量吸水率的影响。结果表明:反应体系pH值=10,n(CTAB)∶n(TEOS)=0.06,n(MSDS)∶n(CTAB)=4,晶化温度120℃,晶化时间24h为最佳合成条件。     

粉煤灰合成中孔分子筛MCM-41及其吸附性能

以粉煤灰为初始原料,十六烷基三甲基溴化铵（CTAB）为模板剂采用水热法合成出中孔分子筛MCM-41,采用小角XRD、TEM、氮气吸附-脱附等对样品的物相、比表面积、孔径、孔体积等进行表征,并研究了样品分子筛对镍离子的吸附性能。结果表明：样品具有典型中孔分子筛MCM-41的特性,比表面积为576 m^2/g,平均孔径为5.53 nm;Ni^2＋能定量吸附在样品分子筛上,最大去除率可达到96%,吸附性能符合Langmuir吸附方程特征,并且随吸附液pH的增大,Ni^2＋去除率也随之增加。     

改性中孔分子筛MCM-41的合成研究

采用水热法合成了纯硅中孔分子筛MCM-41(Mobile Crystalline Material简称MCI),用A1、B原子和结构导向剂OP-10对纯硅MCM-41进行了改性,通过IR、SAXRD、N2吸附-脱附、TEM等技术对其物理化学性能进行表征.对于引入Al、B原子制备的改性MCM-41,考察了模板剂比例、Si...     

SDBS改性沸石吸附亚甲基蓝的性能研究

研究了十二烷基苯磺酸钠(SDBS)改性沸石对染料亚甲基蓝的吸附性能与机理,探讨了温度、亚甲基蓝初始浓度以及溶液中离子强度等因素对吸附的影响.结果表明,SDBS改性沸石吸附亚甲基蓝的平衡时间为25 mim左右.改性沸石吸附亚甲基蓝的吸附等温线与Freundlich型(R~2=0.9334)和Langmuir型(R~2=0.9078)均拟合较好,其吸附动力学符合伪二级动力学方程.     

改性柿叶对亚甲基蓝的吸附性能

研究改性柿叶对亚甲基蓝的吸附性能,探讨了吸附剂用量、吸附时间、初始浓度、pH值、温度等因素对吸附性能的影响,结果显示:硝酸改性可明显提高柿叶对亚甲基蓝的吸附效果。室温下1L亚甲基蓝溶液(40mg/L),当吸附剂用量1g、吸附2.0h,溶液pH=5~11时吸附效果较好,吸附行为更符合Langmuir吸附等温式,饱和吸附量为100.4mg/g。     

有机弱碱体系中介孔分子筛MCM-41的合成与表征

在有机弱碱无水乙二胺为碱介质的条件下(pH≈10) ,以阳离子表面活性剂十六烷基三甲基溴化铵(CTAB)为模板剂,以正硅酸乙酯(TEOS)为硅源,在室温下合成了介孔分子筛MCM-41。与在强碱水热体系中合成的样品相比,室温弱碱体系中合成的样品具有孔道短程有序度高等特点。详细考察了晶化时间、表面活性剂浓度和晶化温度对产物结构的影响。用XRD对所合成的产物进行表征,结果表明,晶化时间越长,所得到产物的有序度越高;随着表面活性剂质量分数的增加,所合成产物的结构和晶型的完整性越高,但并不是表面活性剂的质量分数越大越好,当表面活性剂的质量分数大于6%时,就呈现下降的趋势;随着晶化温度的升高,所得样品的规整性变差,但晶格参数a₀随温度的升高而呈现变大的趋势。     

MCM-41介孔分子筛改性研究新进展

针对目前研制的MCM-41介孔分子筛因水热稳定性较差、孔径过小、难以用于重油加工等方面的缺陷,综述了国内外对MCM-41介孔分子筛改性研究的新进展,尤其是扩大分子筛孔径、提高水热稳定性、引入杂原子和后处理等方面的最新研究。     

制备条件对介孔分子筛MCM-41形貌的影响研究

本文以正硅酸乙酯(TEOS)为硅源,十六烷基三甲基溴化铵(CTAB)为介孔模板剂制备MCM-41介孔分子筛,通过改变制备体系条件来调控MCM-41的形貌,考察了制备体系水用量、制备体系氨水用量、TEOS滴加速率对所得MCM-41产物形貌的影响。结果表明:制备体系水用量和氨水用量增大会使所得产物由棒状向球形颗粒转变,TEOS滴加速率加快有利于形成尺寸均匀的棒状MCM-41。最后对MCM-41形貌演变过程进行了分析。     

用于氧化反应的改性介孔分子筛MCM-41研究进展

主要从金属掺杂、杂多酸负载和有机官能化等方面详细介绍了改性的MCM-41分子筛作为催化剂在氧化反应中的应用情况,分析了其优缺点。今后的研究重点将是进一步提高改性材料MCM-41分子筛的活性,解决活性组分溶脱现象以及水热稳定性等问题。     

Acidity and catalytic activity of the mesoporous aluminosilicate molecular sieve MCM-41

The acidity and catalytic properties of aluminosilicate mesoporous molecular sieves with the MCM-41 structure and bulk Si/Al ratios in the 10–60 range have been investigated. The incorporation of 4-coordinate aluminium into the structure of MCM-41 generates both BrØnsted and Lewis acid sites in amounts increasing with the degree of incorporation. However, the BrØnsted/Lewis acid population ratio is independent of the content of aluminium. The number and strength of acid sites generated are comparable to those of a pillared acid-activated clay and lower than in zeolite H-Y with Si/Al=3.65. Aluminosilicate MCM-41 is a moderate catalyst for the conversion of cumene which proceeds predominantly via catalytic cracking to propene and benzene. The sample of MCM-41 with the highest content of framework aluminium (Si/Al=10) has the largest number of BrØnsted acid sites and exhibits highest catalytic activity.     

Methanol oxidation on LaCo mixed oxide supported onto MCM-41 molecular sieve

Lanthanum cobaltate LaCoO_x supported onto MCM-41 mesoporous molecular sieve was prepared by in-situ oxidative decomposition of mixed LaCo citrate complexes inside the mesopores of this support. The prepared materials were characterized by EDX, EPR and UV-Vis DRS techniques as well as by N₂-BET measurements. The nanosized LaCoO_x particles within the mesopores of MCM-41 matrix contains cobalt atoms in lower than Co(III) average oxidation state. Also, the supported cobaltate does not form short-range order species of LaCoO₃ but presents as the highly disordered, oxygen deficient Co oxide nanophase. Catalytic activity in MeOH oxidation was tested using both conventional fixed-bed flow system and “operando” mode of DRIFT technique. The very high activity of MCM-41-supported cobaltate is not only due to highly dispersed LaCoO₃ phase but also because of rather low oxidation state of Co.     

New acid catalyst comprising heteropoly acid on a mesoporous molecular sieve MCM-41

New solid acid catalysts, consisting of heteropoly acid (HPA) H₃PW₁₂O₄₀ (PW) supported on a mesoporous pure-silica molecular sieve MCM-41, have been prepared and characterized by nitrogen physisorption, X-ray diffraction, FT-IR, and³¹P magic angle spinning NMR. The PW/MCM-41 compositions with PW loadings from 10 to 50 wt% have 30 Å uniformly-sized mesopores. HPA retains the Keggin structure on the MCM-41 surface and forms finely dispersed HPA species. No HPA crystal phase is developed even at HPA loadings as high as 50 wt%. PW/MCM-41 exhibits higher catalytic activity than H₂SO₄ or bulk PW in liquid-phase alkylation of 4-t-butylphenol (TBP) by isobutene and styrene. In the alkylation of TBP by styrene, PW/MCM-41 shows a size selectivity compared to bulk PW and PW/SiO₂, providing higher yields of a 2-(1-phenylethyl)-4-t-butylphenol, at the expense of the more bulky 2,6-bis-(1-phenylethyl)-4-t-butylphenol. The PW/MCM-41 compositions, having strong acid sites and a regular mesoporous system, are promising catalysts for the acid-type conversion and formation of organic compounds of large molecular size.