改性介孔硅负载铂催化合成农用增效剂

通过壳聚糖(CS)改性介孔二氧化硅,并负载铂得到Pt/CS-SiO_2催化剂,采用红外光谱(FTIR)、氮气吸附脱附(BET)、热重分析(TG)等对催化剂进行表征,同时考察了Pt/CS-SiO_2催化聚醚和三硅氧烷反应合成农用增效剂。结果表明:Pt成功负载在改性介孔硅上,Pt含量为0.85%;催化剂具有良好的重复使用性,使用7次后仍有较高活性,转化率和选择性均在90%以上;合成农用增效剂的最优工艺为n(MDHM):n(HDE)=1:1.1,反应温度为105℃,反应时间为3 h。测试产物在不同pH的水溶液中的水解性能,发现其在中性条件下可以比较稳定地存在。     

氮掺杂介孔碳纳米球负载铂催化剂在肉桂醛选择性加氢中的催化性能研究

以多巴胺为碳源和氮源、F127为软模板制备氮掺杂有序介孔碳纳米球（NOMCS）,并以其为载体制备Pt催化剂（Pt/NOMCS）。通过TEM、XPS、OEA、Raman和N₂吸附等手段对材料进行表征。将制备的Pt/NOMCS用于肉桂醛（CAL）选择性加氢模型反应,并研究其催化性能。结果表明,与商用介孔炭（MC）和活性炭（AC）负载Pt催化剂（Pt/MC和Pt/AC）相比,Pt/NOMCS在CAL选择性加氢中显示出较高的催化活性(反应速率常数k=（0.37±0.02） h^-1)和选择性（转化率为90%时的肉桂醇选择性约为75%）。循环实验4次后,Pt/NOMCS显示出较好的可回收性能。     

微波辅助ZrO2-SO2-4/SBA-15催化合成棕榈酸甲酯

以三嵌段醚共聚物P123作为模板剂、正硅酸乙酯为硅源,合成介孔分子筛SBA-15。以SBA-15为载体,利用尿素水解法制备ZrO₂-SO^2-₄改性的固体酸催化剂,对其进行表征。实验结果表明,合成的固体酸催化剂具有典型的介孔结构特征。将催化剂应用于微波法催化合成棕榈酸甲酯,考察反应时间、反应温度、辐射功率、酸醇物质的量比和催化剂用量对酯化率的影响,结果表明,在n（十六酸）∶n（甲醇）=1∶15、SZ/SBA-15催化剂用量0.8 g、反应时间20 min、反应温度40 ℃和微波辐射功率400 W条件下,酯化率可达87.70%,微波反应时间较传统合成方法大大缩短。     

Pt/TiO2/ZSM-5催化剂的制备及其催化转化正丁烷

采用溶胶-凝胶法和等体积浸渍法,分别对ZSM-5分子筛进行TiO₂改性和Pt负载,获得了具有脱氢-裂解双功能的Pt/TiO₂/ZSM-5催化剂,采用XRD、N₂吸附-脱附、TEM、XPS和NH₃-TPD对样品的晶体结构,孔结构、形貌、活性金属价态和酸性质等进行了表征,并研究了正丁烷在此催化剂上催化转化制备低碳烯烃的反应规律。研究结果表明,TiO₂的引入,一方面使得改性后的ZSM-5分子筛获得了额外的酸性中心,特别是强酸性位含量的增加,有助于促进正丁烷的活化;另一方面Pt与TiO₂之间存在“金属-载体”强相互作用（SMSI）,在H₂还原气氛下,Pt能够促进TiO₂的还原,生成Ti³⁺物种,而Ti³⁺的存在增加了Pt周围的电荷密度,降低了Pt对低碳烯烃（C₂⁼～C₃⁼）的吸附能力,抑制了深度脱氢和生焦反应,从而提高双功能催化剂对烯烃的选择性。当H₂还原温度为450℃时,Pt/10TiO₂/ZSM-5催化剂在625℃下的正丁烷转化率为76.1%,低碳烯烃（C₂⁼～C₃⁼）收率为50.9%,分别比Pt/ZSM-5催化剂提高了16.7%和12.6%。     

含Ni介孔分子筛的合成及其对苯加氢催化性能

采用水热法合成出不含镍和含镍的硅基介孔分子筛.利用XRD、FT-IR、TPR、TEM和比表面孔径测定等手段对样品进行了表征.结果表明：合成出有序性好的介孔分子筛（MCM-41）,550 ℃焙烧可以将模板剂有效去除,所合成介孔分子筛负载Pt后介孔有序性降低,但是介孔结构仍然存在.苯催化加氢反应研究表明：不含Ni的介孔分子筛不具有加氢活性,当将其负载Pt后具有苯加氢催化活性;含Ni介孔分子筛本身具有苯加氢活性,含Ni介孔分子筛负载Pt后苯加氢催化活性有较大的提高,所有样品的环己烷选择性都接近100 %,说明含Ni介孔分子筛可以直接作为苯加氢反应的催化剂或作为苯加氢催化剂良好的载体.     

介孔SiO2吸附CO2的性能研究

以正硅酸乙酯（TEOS）为硅源,端氨基聚氧化丙烯醚（D2000）为模板剂,在水和乙醇的混合溶液中合成了蠕虫状介孔结构的介孔SiO₂（记为MSU-J）。采用物理浸渍的方法利用四乙烯五胺（TEPA）改性介孔MSU-J。采用红外、N₂吸附/脱附、元素分析表征改性介孔SiO₂。红外测试表明,经过物理浸渍可以将有机胺负载到介孔SiO₂上。N₂吸附/脱附试验表明,经过氨基修饰后,介孔SiO₂的介孔结构没有发生变化,但是介孔的孔容、孔径以及比表面积随着氨基浸渍量的增加而减小。在25℃和45℃,0.1 MPa下的纯CO₂吸附试验表明,氨基改性材料对CO₂吸附效果明显提高。当浸渍量为20%、吸附条件为25℃/0.1 MPa时,吸附量达到最大值138.6mg/g。当氨基含量继续增加时,吸附量反而降低。循环性试验表明,制备的吸附剂具有良好的循环性能,循环使用6次,材料的吸附量下降很少。     

NPS-1负载磷钨酸催化合成4-叔丁基-2-(α-甲基苄基）苯酚

以介孔分子筛NPS-1负载12-磷钨酸杂多酸为催化剂,4-叔丁基苯酚和苯乙烯为原料,合成4-叔丁基-2-（α-甲基苄基）苯酚（t-BAMBP）。采用正交实验研究介孔材料NPS-1负载12-磷钨酸对t-BAMBP合成反应的催化活性,考察反应温度、反应时间、原料配比和催化剂用量对t-BAMBP收率的影响。优化的工艺条件为：反应温度70 ℃,反应时间30 min,n（苯乙烯）∶n(4-叔丁基苯酚)=1.3∶1,催化剂用量为4-叔丁基苯酚质量的0.2%,t-BAMBP收率70.3%。     

介孔Cu/MS-1催化羟基化苯酚合成苯二酚

以十六烷基三甲基溴化铵（CTAB）为模板剂,采用溶胶凝胶法合成具有介孔的S-1载体（MS-1）,浸渍法制备Cu/MS-1催化剂,用于以双氧水为氧化剂、苯酚直接羟基化合成苯二酚的反应,运用正交实验法[L₂₅（5⁶）]对反应条件进行优化。使用X射线电子能谱（XPS）、N₂的等温吸附-脱附和 H₂的程序升温还原等方法对催化剂的结构和性能做了表征。结果表明：具有介孔的Cu/MS-1有利于反应物和生成物的快速扩散,催化性能明显优于Cu/S-1;高分散CuO相对质量分数最高的5.5% Cu/MS-1的催化活性最好,在优化条件下,苯二酚的产率达到47.2%,选择性为86.7%。具有介孔和MFI结构的Cu/MS-1稳定性强,重复使用5次后,苯二酚的产率仍达43.2%。     

二氧化硅负载磷钨酸催化合成丁醛乙二醇缩醛

本文以二氧化硅负载磷钨酸(H₃PW₁₂O₄₀/SiO₂)为催化剂,丁醛和乙二醇为原料合成丁醛乙二醇缩醛,探讨了H₃PW₁₂O₄₀/SiO₂/SiO₂对缩醛反应的催化活性,研究了醛醇物质的量比、催化剂用量、反应时间等因素对产物收率的影响。实验结果表明:H₃PW₁₂O₄₀/SiO₂/SiO₂是合成丁醛乙二醇缩醛的良好催化剂。在固定丁醛用量为0.2mol的情况下,n（丁醛）:n（乙二醇）=1:1.4,催化剂的用量占反应物料总质量的1%,环已烷用量为4mL,反应时间为45min的条件下,产品收率可达77.6%。     

载体结构对锡铁负载型催化剂脱硝性能的影响

利用凹凸棒土（ATP）、活性炭（AC）、介孔硅（MCM-41）、二氧化钛（TiO₂）这4种孔结构不同的载体,通过水热法制备了以Fe₂O₃为催化剂主活性组分、SnO₂为辅活性组分的锡铁负载型催化剂。催化剂的微观结构通过BET和SEM测试,并在催化剂评价装置中模拟烟气组成,考察锡铁负载型催化剂在反应温度为80～280℃、脱硝空速为32000～48000h^-1范围内的选择性催化还原（SCR）性能。同时考察了SO₂与H₂O对1/2SnFe/ATP催化剂的影响。实验表明,载体可能为催化剂提供大量Brønsted酸性位点,有利于反应气体吸附。1/2SnFe/ATP催化剂表现出最佳的SCR脱硝性能,在200℃时实现最高96.4%的NO转化率,而且由其抗硫性及其抗水性实验表明：SO₂单独作用于催化剂时,脱硝效率降低迟缓,切断二氧化硫后仍能恢复到85%以上。同时加入水和二氧化硫后,将会导致脱硝效率急剧下降。停止加入后,催化剂效率又开始慢慢恢复,效率可以恢复达到70%以上。     

聚醚改性三硅氧烷的合成工艺研究

以烯丙基聚醚与七甲基三硅氧烷为原料,通过硅氢加成反应合成出聚醚改性三硅氧烷。用IR对其结构进行表征,研究了催化剂用量、反应温度、反应时间、烯丙基聚醚与七甲基三硅氧烷的量之比[n(醚)/n(硅)]对七甲基三硅氧烷转化率的影响以及七甲基三硅氧烷转化率与产物表面张力的关系。结果表明,较佳反应条件是n(醚)/n(硅)为1.2、铂原子相对于七甲基三硅氧烷的质量分数为0.00075%、反应时间1 h、反应温度100～110℃。在此条件下合成出的聚醚改性三硅氧烷的0.1%的水溶液的表面张力为20.3 mN/m,七甲基三硅氧烷的转化率为98.1%。     

双子型聚氧乙烯醚三硅氧烷表面活性剂的合成与性能研究

以烯丙基聚氧乙烯醚与六亚甲基二异氰酸酯为原料,在锡催化剂的作用下合成六亚甲基二氨基甲酸酯,然后在铂催化剂作用下,与1,1,1,3,5,5,5-七甲基三硅氧烷(MDHM)进行硅氢化加成反应制得双子型(Gemini)聚氧乙烯醚三硅氧烷表面活性剂(GPETS)。目标产物GPETS的结构用IR和1HNMR进行了表征,并研究了其表面活性。在浓度为5.9×10-5mol/L时,可以将水的表面张力降至22.0 mN/m。在不同的pH下研究其水解稳定性,并与相应的聚氧乙烯醚三硅氧烷表面活性剂对比,结果表明,GPETS的水解稳定性优于后者,适用于更宽的pH范围。     

One-Step Hydrogenation/Esterification Activity Enhancement Over Bifunctional Mesoporous Organic–Inorganic Hybrid Silicas

Bifunctional mesoporous organic–inorganic hybrid silica incorporating both platinum and organosulfonic acid groups were synthesized for use in simultaneously catalyzing the one-step hydrogenation/esterification (OHE) of acetic acid and acetaldehyde, which was considered as a model reaction for the upgrading of biomass-derived bio-oil. The work explored optimizing the synthesis procedure to generate a bifunctional catalyst with enhanced combined activity for the OHE reaction. The presence of Pt was found to enhance the acidic properties of the organosulfonic acid functionalized silica. The mechanism by which the Pt incorporation affected the acid sites was investigated by the using XPS, FT-IR, FT-Raman characterization. The XPS results indicated the presence of electron transfer between the Pt and –SO₃H groups. The FT-IR and FT-Raman results, which were in agreement with XPS, demonstrated an electron density increase for S and a S–O bond energy increase, which was proposed to be the reason for the acidity enhancement due to the presence of Pt. Additionally, arenesulfonic acid groups were substituted for propylsulfonic acid groups and the resulting material had higher catalytic activity due to the increased acid strength. An optimal synthesis procedure was demonstrated in which the Pt was first impregnated on the mesoporous silica using reductive deposition. Then Pt was activated and the material further modified by grafting on arenesulfonic acid groups. The resulting catalyst was about four times more active than the original base case bifunctional material.     

Increased Metal Utilization in Carbon‐Supported Pt Catalysts by Adsorption of Preformed Pt Nanoparticles on Colloidal Silica

Pt/C electrocatalysts, aimed at maximizing the electrochemical surface area (ECSA) and consequently the specific mass activity of fuel cell reactions, are obtained by firstly depositing Pt nanoparticles on colloidal silica (Pt‐silica), followed by the adsorption of the latter onto a carbon support. This method of catalyst preparation increases Pt metal utilization and generates accessible void space in the interpenetrating particle network of carbon and silica for the facile transport of reactants and products. Both electrochemical hydrogen adsorption/desorption and CO oxidation measurements show an increase in the ECSA using this approach. Methanol electrooxidation is used as a test reaction to evaluate the catalytic activity. It is found that the silica modified catalyst is three times as active as a catalyst prepared without silica, under otherwise identical conditions.     

Electrodeposited platinum catalysts over hierarchical carbon monolithic support

Mesoporous deposits of platinum catalysts were electrodeposited over monolith carbon with hierarchical porous structure. The liquid crystal used as a template allowed the electrodeposition of the catalyst on the outer region of the carbon with low penetration in the porous structure. The platinum hexagonal mesostructured deposits exhibits an excellent stability enhanced by the roughness of the carbon support. The mass activity for the electrooxidation of methanol of the mesoporous Pt catalyst supported on the hierarchical carbon is similar to that observed on gold and to that reported for commercial Pt nanoparticulated catalysts, even when this catalyst has a smaller Pt load than the commercial one. Also, the poisoning rate of the mesoporous catalyst is lower than that observed for the commercial catalyst. The integrated system of structured materials could be suitable for the fabrication of modified electrodes in small scale applications.     

One pot synthesis of cinchona functionalized mesoporous silica and its enantioselectivity

Cinchona functionalized mesoporous silica is synthesized by one pot synthesis method. The main silica precursor (TEOS) is co-condensed with a cinchonidine molecule linked organosilane which is renovated by triethoxy silane moiety at its C11 position to yield cinchona functionalized silica. The subsequent deposition of Pt nanoparticles over functionalized silica provides a catalytic system for the enantioselective hydrogenation of ??-activated ketone (Orito??s reaction). Thus-developed catalyst system is found to be enantioselective with an enantiomeric excess (e.e) of 35.6%.     

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。     

Highly efficient metal-free phosphorus-doped platelet ordered mesoporous carbon for electrocatalytic oxygen reduction

Platinum-free electrocatalysts especially, various heteroatom-doped carbon nanostructures have attracted particular attraction as plausible solution for commercializing fuel cell technology. In this direction, novel phosphorus-doped platelet ordered mesoporous carbon (P-pOMC) is developed for the first time as metal-free electrocatalyst for alkaline oxygen reduction reaction. The P-pOMC is synthesized by nanocasting method using platelet ordered mesoporous silica as template. Various characterizations reveal that the P-pOMC materials have covalently bound P atoms with carbon framework for facilitation of oxygen reduction reaction (ORR) and also have very high surface area with uniform distribution of short mesoporous channels for unhindered mass transfer. Combination of P doping and excellent surface properties empowers the newly-developed P-pOMC catalyst to show high ORR activity nearly equal to that of state of the art Pt catalyst along with superior long-term stability and excellent methanol tolerance.     

Novel Pd-BTP/SiO2 as an Effective Heterogeneous Catalyst for Heck Reactions

A highly efficient and reusable catalyst, palladium (II) complex supported on functionalized silica, was prepared by anchoring palladium (II) onto 2,6-bis(5,6-dimethyl-1,2,4-triazine-3-yl)pyridine [BTP]-modified mesoporous silica (labeled as Pd-BTP/SiO₂). The catalyst was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), and Brunauer Emmett Teller (BET) analysis. Its catalytic performance was tested for the Heck coupling reactions between aryl halides with acrylic acid or styrene, and good to excellent results (higher conversions 87–96% and yields 66–78%) were obtained. The catalyst system was stable under the reaction conditions and could be successfully reused more than five times without the loss of catalytic activity.     

A co-pyrolysis route to synthesize nitrogen doped multiwall carbon nanotubes for oxygen reduction reaction

Nitrogen-doped multiwall carbon nanotubes (N-MWCNTs) have been synthesized by a co-pyrolysis route of iron(II) phthalocyanine (FePc) loaded and PEO₂₀–PPO₇₀–PEO₂₀ retained in mesoporous silica. In this process, FePc was used as both Fe-catalyst, carbon and nitrogen sources, and P123-containing mesoporous silica was employed as both the substrate and carbon seeds/source for the growth of N-MWCNTs. The obtained samples have well-defined morphology and graphitic structure, and show high electrochemical catalytic activity and stability for oxygen reduction reaction, attributing to the highly graphitic structure and the pyridinic-type nitrogen in the N-MWCNTs. The power density of a single fuel cell using N-MWCNT as cathodic catalyst was measured to be 67.7% of that of a standard single cell using 40% Pt/C as cathodic catalyst.