新型固体碱介孔MgO-ZrO2的制备及催化性能研究

采用可控的溶胶-凝胶法制备了一种新型的介孔MgO-zr02固体碱,其具有优良的热稳定性,在700℃依然能保持着介孔特征.这种新型的固体碱具有较高的比表面积和较大的孔道结构,同时纳米级的Mg0和zro2颗粒紧密联结,具有比常规固体碱催化剂更高的活性和稳定性.该介孔固体碱在甲醇与环氧丙烷合成醇醚反应中表现出良好的催化性能.     

新型有序介孔炭基固体酸的制备及其催化双酚A合成

采用软模板法制得具有高度有序介孔孔道结构、高密度-SO₃H基团的新型有序介孔炭基固体酸催化剂。通过N₂吸附-脱附、X射线衍射、透射电镜、EDX能谱以及酸碱滴定等手段对催化剂进行了表征,考察了炭化温度对介孔炭基固体酸催化剂介孔孔道结构、表面酸性以及催化活性的影响。结果表明,500 ℃是最适宜的炭化温度,该炭化温度下制备的催化剂介观有序性较好且酸密度较高。所得的催化剂在丙酮与苯酚缩合生成双酚A的反应中表现出明显高于其它3种固体酸催化剂（001×7,D072,无定型炭基固体磺酸）的活性。可见,有序介孔炭基固体酸是一种高效的新型固体酸催化剂,在双酚A领域具有较好的应用潜力。     

负载型固体碱催化剂在酯交换反应中的研究进展

酯交换法是目前生物柴油工业生产的主要方法,负载型固体碱催化剂是催化酯交换反应的一种环境友好型固体碱催化剂.介绍了国内外负载型固体碱催化剂(主要包括以Al2O3、活性炭、ZrO2、微孔分子筛和介孔分子筛为载体的固体碱催化剂)在酯交换反应中的研究情况,同时提出今后应进一步深入研究符合环保要求和工业化需求的新型负载型固体碱催...     

水热碱蚀与碱溶滤联合处理制备介孔丝光沸石

以硅酸钠溶胶和铝酸钠为硅、铝源,采用水热合成和离子交换法制备了质子型丝光沸石(H-MOR)。研究水热碱蚀与碱溶滤联合处理对H-MOR改性样品的介孔结构、晶体形貌、组成及酸性质的影响。结果表明:用初始浸渍液对H-MOR进行水热碱蚀,H-MOR骨架脱硅选择性高,晶体含有均一的筛状介孔;水热碱蚀与一次碱溶滤处理的样品具有尺度分布较窄的槽形介孔,沸石骨架硅铝比降低而介孔率增加;再度进行碱溶滤处理,沸石的最可几介孔尺寸和累计介孔体积进一步增大,而残留抽出物(无定形SiO2–Al2O3)的硅铝比为生成介孔丝光沸石晶相的5倍以上。联合碱处理的丝光沸石样品具有骨架脱硅选择性和介孔率高、介孔分布(4.4~5.7nm)可控的特性,其结晶度、固有微孔结构和酸性质退化程度较低。     

磺酸基官能化介孔材料的表征及其催化性能

由高水热稳定的巯基官能化介孔硅基材料经氧化得到磺酸基官能化介孔固体酸催化剂。经过一系列的表征测试,所得固体酸具有发达的孔道结构和大量Br尴nsted酸性位。将其应用于苯甲醛与醇类缩合反应中,与传统沸石固体酸催化剂HY相比,显示了更好的催化性能,缩醛收率在90%左右。所合成的磺酸基官能化介孔固体酸催化剂的催化性能基本不受醇类分子体积影响,具有很好的重复使用性能。     

固体碱催化酯交换反应制备生物柴油研究进展

介绍了非负载型和负载型2类固体碱催化剂用于制备生物柴油的研究进展,采用酯交换法因其无需消耗大量能量、操作方法简单,成为制备生物柴油的主要方法,并随着负载型固体碱催化剂载体的纳米化、介孔化,纳米级以及以分子筛作为载体的固体碱催化剂将成为一个主要的研究方向。认为开发更加稳定、耐水、耐酸的固体碱催化将是今后固体碱催化剂的研究重点。     

丝光沸石硅铝比对骨架脱硅衍生介孔结构的影响

用水热合成和铵交换法制备系列氢型丝光沸石(H-MOR),通过水热碱蚀与碱溶滤联合处理对H-MOR样品进行选择性脱硅和介孔改性.研究H-MOR骨架Si/Al比对改性沸石的介孔结构、酸性和水热稳定性的影响.N2吸附结果表明,碱处理沸石的介孔率随H-MOR硅铝比减少而增加;典型样品(n(Si) /n(Al) 9.43)具有附加介孔结构,介孔体积可达0.082 cm3/g,最可几孔径为4.6 nm;SEM观察显示,改性沸石的介孔结构源于脱硅产生的结构缺陷,晶内介孔呈无序分布;ICP和EDX分析证实,联合碱处理促进H-MOR晶体选择性脱硅(脱硅率均大于93.1％);水热稳定性和NH3-TPD数据表明,介孔改性丝光沸石较好地保持了前体的结晶性和水热稳定性,其酸性与对应H-MOR沸石相匹配.骨架硅铝比影响改性MOR沸石的介孔率,但与沸石脱硅率无相关性.     

后处理改性对HZSM-5沸石丁烯裂解性能的影响

采用不同后处理手段(碱处理、水汽处理以及碱处理-水汽处理)对HZSM-5沸石的孔结构和酸性质进行了调变,并对其丁烯裂解性能进行了研究。运用N₂吸脱附、扫描电镜(SEM)、X射线衍射(XRD)以及吡啶吸附红外(Py-IR)对后处理改性前后的沸石样品的物理化学性质进行了表征。碱处理后HZSM-5的质子酸量增加,在5～20 nm处具有分布较宽的介孔,其反应活性升高,丙烯选择性下降,但失活速率没有加快。单独水汽处理在2～4 nm处产生介孔,但介孔体积较小。碱处理-水汽处理在2～4和5～20 nm处具有双分布介孔,前者分布较集中,后者分布较宽。单独水汽处理和碱处理-水汽处理的样品可以提高HZSM-5的丙烯选择性,主要归功于酸量的降低;反应2.5 h后具有较稳定的丙烯收率(高碱浓度处理-水汽处理的样品除外)。     

碱处理技术制备微-介孔分子筛的研究进展

碱处理是一种制备微-介孔分子筛的典型方法,具有成本低、快速和产率高等优点。综述微-介孔分子筛的发展由来,概述金属组分改性对微-介孔分子筛的影响,对表征技术进行深入探讨,以更好地解释微-介孔结构的形成机理,得出碱处理对分子筛的孔结构、酸性以及金属组分产生重要影响。采用碱处理制备的分子筛在各种反应中表现出良好的催化性能,具有广阔的应用前景。     

介孔有机硅分子筛表面的碱改性及其催化性能

采用水热法直接合成出表面含有机碱中心的介孔有机硅分子筛PMOs催化剂.XRD分析结果表明,3种有机碱改性的催化剂都具有介孔分子筛的完整晶体结构.红外光谱IR分析结果证明了在分子筛的表面含有机碱基团.热失重（TGA）分析认为各种有机碱中心在有机介孔分子筛表面的热稳定性高于300 ℃,骨架中的乙烷基在低于500 ℃下保持稳定.甲醇与十八碳烯酸的酯化反应结果表明,十八碳烯酸的转化率随碱强度和碱中心数增加而升高,催化剂活性的顺序为PMO-DN>PMO-Py>PMO-N;3个催化剂反应后的XRD衍射强度比反应前都加强,分析认为与模板剂的脱除方法——碱化乙醇溶液有关.     

Mesoporous CaO–ZrO2 nano-oxides: A novel solid base with high activity and stability

A new solid base, mesoporous CaO–ZrO₂ nano-oxides, was prepared via appropriate sol–gel process. It was found that such solid base showed high basicity and stability. Temperature programmed desorption of CO₂ confirmed that both weak and strong basic sites coexisted on the surface of CaO–ZrO₂ and the basicity could be modified by adjusting Ca/Zr molar ratio of the nano-oxides. The mesoporous CaO–ZrO₂ nano-oxides showed high thermal stability, since X-ray diffraction (XRD) and transmission electron microscopies (TEM) proved that the mesoporous network of this material preserved well even up to 700 °C. At the same time, XRD and Raman spectra indicated that Ca²⁺ incorporated into t-ZrO₂ lattice and the basic sites were firmly anchored to the substrate. As a result, this novel solid base showed remarkable activity and durability in the synthesis of dimethyl carbonate from methanol and propylene carbonate.     

CaO–ZrO2 Solid Solution: A Highly Stable Catalyst for the Synthesis of Dimethyl Carbonate from Propylene Carbonate and Methanol

CaO–ZrO₂ prepared by co-precipitation showed to be a well-performed catalyst for the transesterification of propylene carbonate (PC) and methanol. The characterization by X-ray powered diffraction (XRD) and Raman spectroscopy indicated that CaO was doped into the lattice of ZrO₂ to form CaO–ZrO₂ solid solution. Such a solid solution was a strong solid base, which was proved by CO₂ temperature program desorption (CO₂-TPD). As a result, the catalyst showed high stability towards the transesterification of propylene carbonate and methanol into dimethyl carbonate with high PC conversion, especially being subjected to the continuous production of dimethyl carbonate at reactive distillation reactor for 250 h without any obvious loss of activity at the PC conversion of 95%.     

Pd/CMK-3的合成及其在Suzuki-Miyaura碳-碳偶联反应中的应用

利用介孔二氧化硅（SBA-15）为模板、蔗糖为碳源,制备了有序介孔碳材料CMK-3,然后以CMK-3为载体,利用浸渍还原法得到介孔碳负载Pd纳米粒子的复合催化剂（Pd/CMK-3）,通过XRD、TEM以及氮气吸附-脱附等手段对催化剂的微结构和组分进行分析,结果表明CMK-3为有序介孔结构,孔径约为5nm,Pd/CMK-3保留了介孔结构,且孔道中负载有不同尺寸的Pd粒子。应用于无配体催化的Suzuki-Miyaura相似文献   

高稳定性介孔MgO-ZrO_2纳米复合物对CO_2吸附性能研究

用溶胶-凝胶法制备了介孔MgO-ZrO2纳米复合物,并通过XRD、氮吸附和CO2-TPD等手段表征了材料的结构特征和表面性质。XRD、氮吸附结果表明此纳米复合物具有典型的介孔结构,比表面积达183~212 m2/g,并且有较好的热稳定性,在700℃以下介孔孔道不会坍塌。另一方面,这种纳米复合物表面具有适中的碱性,其碱性位与基体结合牢固,稳定性好。由于其具有发达的孔隙和适中的碱性,二氧化碳在其表面的吸附量达1.6 mmol/g,且经数次循环后材料的吸附性能无明显下降。     

固体碱性位对碳酸二甲酯与苯乙酮反应的影响

考察了固体碱不同的碱性位对碳酸二甲酯和苯乙酮反应合成苯甲酸甲酯的影响,并讨论了反应在不同碱性位上的反应机理。实验结果表明,由表面羟基引起的弱碱位有利于苯乙酮自身缩合反应(主产物为1,3-二苯基-2-烯基-丁酮)的进行,而Bronsted-Lewis酸碱离子对和固体碱表面配位不饱和的O2-所造成的强碱位由有利于碳酸二甲酯的甲氧基羰基化产物(主产物为苯甲酸甲酯和乙酸甲酯)的生成。     

Synthesis of Phenylethenyl Methyl Carbonate by Methoxycarbonylation of Phenylacetaldehyde with Dimethyl Carbonate

A novel and convenient route for the synthesis of phenylethenyl methyl carbonate by the methoxycarbonylation of phenylacetaldehyde with dimethyl carbonate was developed in the presence of solid base catalysts. The results showed that solid bases with moderate strength such as MgO favored the formation of phenylethenyl methyl carbonate, and the yield of phenylethenyl methyl carbonate could be linearly correlated with the amount of moderate basic sites. The function of basic catalysts was mainly ascribed to the activation of phenylacetaldehyde via the abstraction of α‐H by the base sites.     

固体强碱绿色催化环氧丙烷水解合成1,2-丙二醇

该文制备了不同碱强度的固体碱催化剂,并应用于环氧丙烷(PO)水解合成1,2-丙二醇的反应。结果表明:随着催化剂碱强度的增加,环氧丙烷的转化率不断升高;说明强碱催化剂有利于环氧丙烷水解反应。在此基础上,作者系统考察了催化剂用量、反应温度、原料摩尔比和反应时间对催化性能的影响。结果表明:当催化剂CaO-ZrO2质量为反应原料质量的1.0%,反应温度为120℃,反应原料配比为:n(H2O)∶n(PO)=5∶1,反应时间2h时,其催化效果较优,环氧丙烷转化率最高为92.3%,1,2-丙二醇选择性可达89.4%。     

生产条件对碱式碳酸铜产率影响的研究

以硝酸铜和碳酸钠为原料生产碱式碳酸铜,通过正交法考察和研究了硝酸铜和碳酸钠的浓度、反应温度、碳酸钠与硝酸铜的配比对碱式碳酸铜产率的影响。结果表明,硝酸铜浓度为0.45 mol/L,碳酸钠浓度为0.55 mol/L,反应温度为58℃,碳酸钠与硝酸铜的摩尔配比为1.5∶1,碱式碳酸铜的产率为94.29%。     

Preparation and Characterization of Novel Poly(Urethane-Imide) Nanocomposite Based on Graphene,Graphene Oxide and Reduced Graphene Oxide

In this work in-situ preparation of novel poly(urethane-imide)/graphene, graphene oxide and reduced graphene oxide nanocomposite is reported by the reaction of 4,4´-diphenylmethane diisocyanate, polypropylene glycol, 3,3’,4,4′-benzophenone tetra carboxylic dianhydride and nanomaterials in the loadings levels of 0.5, 1.5, 2.5, and 3.5 pbw in propylene carbonate as an alternative green solvent. The synthesized poly(urethane-imide) nanocomposite was characterized by Fourier transform infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (¹HNMR), thermogravimetric analysis (TGA), attenuated total reflection (ATR), X-ray diffraction (XRD) and differential scanning calorimetry (DSC), respectively. The resulting nanocomposite showed enhanced thermal stability when compared with pristine and unfilled poly(urethane-imide) sample.     

Enhanced properties of solid solution (CeZr)O2 modified with metal oxides for catalytic oxidation of low-concentration methane

The solid solution (CeZr)O2 catalyst was synthesized, and it was modified with metal oxides by incipient impreg-nation. Morphology and structure were characterized by X-ray diffraction, transmission electron microscope, ni-trogen ad/desorption and H2-temperature program reduction techniques. The catalytic properties of methane oxidation were also investigated. The results showed that solid solution possessed a mesoporous structure and exhibited excellent catalytic performance. The activity of solid solution was improved effectively by nickel dop-ing, and the optimal loading is 15 wt%. The stability of (CeZr)O2 and modified (CeZr)O2 indicated that the struc-ture of pristine solid solution played a key role in promoting molecules diffusion and spatial confining oxide particle sintering.