WO3／ZrO2和MoO3／ZrO2固体超强酸体系研究

研究了浸渍偏钨酸铵和仲钼酸铵的无定形ＺｒＯ２在焙烧过程中钨和钼氧化物表面分散和晶相变化情况。发现于３５０℃焙烧后钨，钼仍以多聚酸根形式分散于ＺｒＯ２表面，用ＸＲＤ法测定的“视阈值”远大于按ＷＯ３和ＭｏＯ３计算的单层分散容量，８００℃焙烧后钨和和钼以ＷＯ３和ＺｒＭｏ２Ｏ８的形式分散于ＺｒＯ２表面上，用ＸＲＤ方法测定的“视阈值”与ＷＯ３和ＺｒＭｏ２Ｏ８的单层分散容量相近。Ｈａｍｍｅｔｔ指示剂法和正戊烷     

固体超强酸研究的最新进展

简要介绍了近年来固体超强酸的发展。目前研究较多的固体超强酸有负载硫酸超强酸、Ｃｓ２．５盐、ＡｌＣｌ３／ＰＳ－ＤＶＢ磺酸树脂体系和全氟磺酸树脂（Ｎａｆｉｏｎ－Ｈ－Ｈ ＰＥＩＥＰ）四种。文章主要阐述了这几种固体超强酸的制备方法及它们的性质比较。     

固体超强酸催化合成富马酸二甲酯的研究

研究了以ZrO2／SO42-固体超强酸催化富马酸和甲醇合成富马酸二甲酯的反应，表征了催化剂的物化性质，探讨了催化剂制备条件、原料配比、反应时间、催化剂用量等工艺参数对收率的影响。催化剂的重复使用实验表明：ZrO2／SO42-是富马酸二甲酯合成的较适宜的催化剂。     

稀土固体超强酸催化合成庚酸丁酯

庚酸丁酯是无色液体 ,具有生苹果香味。主要用以配制苹果型香精 ,是我国 GB2 760— 86规定允许使用的食用香料 ,也可用于有机合成和用作溶剂。通常它是在硫酸催化下由庚酸和正丁醇酯化反应而得[1] 。硫酸虽然活性高 ,价廉 ,但选择性差 ,产品质量不好 ,设备腐蚀严重 ,同时产生大量废液 ,污染环境。为此 ,本实验选用稀土固体超强酸 SO2 - 4/ Ti O2 / La3+作为催化剂进行庚酸与正丁醇的酯化反应。固体超强酸是比 1 0 0 %的硫酸更强的酸 ,即H0 <-1 1 .94的酸[2 ] 。在某些有机催化反应中 ,固体超强酸显示出非常高的催化活性 ,具有不怕水、耐…     

低温陈化法制备SO2-4/WO3-TiO2固体超强酸及性能研究

0引言 固体超强酸的研制是近20年来催化领域中的热点研究课题之一.起初,人们所研制的SO2-4/MxOy型固体超强酸中,MxOy多为ZrO2.近年来,研究者们为得到高酸强度和高催化活性的固体超强酸催化剂,以ZrO2为主体,引入第二组分、第三组分组成复合型催化剂,这方面的研究者颇多[1-4],也取得了一定的成果.     

固体超强酸SO /SiO2-TiO2催化合成异维生素C钠

在异维生素C钠（D-VcNa）的合成过程中,以SO4^2-/SiO2-TiO2复合固体超强酸作为酯化反应催化剂,2-酮基-D-葡萄糖酸（2-KGA）和甲醇为原料,采用精馏脱水酯化工艺,不断除去酯化过程中产生的水.催化剂的最佳焙烧温度为550℃,催化剂用量为2.5%;反应时间3～4 h,产品收率为88.6%,催化剂的重复使用性较好,催化体系优于硫酸法.     

低温陈化法制备SO_4~(2-)/WO_3-TiO_2固体超强酸及性能研究

0引言固体超强酸的研制是近20年来催化领域中的热点研究课题之一。起初,人们所研制的SO42-/MxOy型固体超强酸中,MxOy多为ZrO2。近年来,研究者们为得到高酸强度和高催化活性的固体超强酸催化剂,以ZrO2为主体,引入第二组分、第三组分组成复合型催化剂,这方面的研究者颇多[1~4],也     

SO^2—4／TiO2和SO^2—4／Fe2O3固体超强酸研究

用ＸＲＤ、ＴＧ－ＤＴＧ、ＳＥＭ和化学分析等手段研究了浸渍Ｈ２ＳＯ４的无定形ＴｉＯ２和Ｆｅ２Ｏ３在焙烧过程中的晶化、相变、失水及失硫情况，总结出ＳＯ＾２－４／ＭｘＯｙ型固体超强酸具有与ＳＯ＾２－４／ＺｒＯ２体系相同的形成规律。用ＩＲ光谱和常温正戊烷异构化反应对ＳＯ＾２－４／ＴｉＯ２／Ｆｅ２Ｏ３的超强酸性进行了表征，表明它们与ＳＯ＾２－４／ＺｒＯ２体系具有相似的表面酸位结构，无水状态主要为Ｌ酸位，吸水     

Catalysis of Ruthenium-Metal Oxides Mechanically Mixed with Sulfated Zirconia for Reaction of Butane to Isobutane

A highly active catalyst for the skeletal isomerization of butane to isobutane was obtained by mechanically mixing SO₄/ZrO₂ and Ru/SnO₂; Ru/SO₂ was prepared by impregnating tin hydroxide with a solution of RuCl₃ followed by calcining at 450°C (0.5 wt.% Ru). The catalyst was much more active than Ru-SO₄/ZrO₂ prepared by co-impregnation of zirconia with the Ru and sulfate materials the temperature difference to show the same conversion between both catalysts being 57°C. The effect of mixing of Ru was observed with other metal oxides as supports, Fe₂O₃, Al₂O₃, ZrO₂, TiO₂, and SiO₂; the calcination temperature of the Ru-impregnated hydroxides was 250, 300, and 400°C for the latter three, respectively.     

Sulfated Zirconia: An Efficient Catalyst for Solvent-Free Synthesis of Silyl Ethers Under Mild Conditions

Oximes, allylic, aliphatic, aromatic, cyclic, acyclic, and hetero alcohols are silylated in short reaction times with good yields in the midst of a catalytic amount of sulfated zirconia solid acid catalyst and trimethylsilyl cyanide under nonbasic, solvent-free, and ambient temperature conditions. Selectivity toward O-silyl ether rather than N-silyl ether has been observed. This simple experimental procedure, combined with easy recovery and reusability of the catalyst, is expected to contribute to the development of a clean and environmentally friendly strategy for the synthesis of O-silyl ethers.     

Synthesis and Characterisation of Sulfated Zirconia Sol-Gel Systems

A set of sulfated zirconia xerogels were prepared using a one and two step hydrolysis method, in different vessels (open or closed) and varying the molar ratio R = [HNO₃]/[Zr(On-Pr)₄]. In order to verify the influence of these variables on the gel time and the final samples, physisorpion, quantitative analysis of the sulfate, DTA and DTG, X-ray diffraction at small (SAXS) and wide (WAXS) angles, and FTIR measurements, were employed. The main differences were found regarding samples with different values of R. For samples with R constant, the preparation method and the kind of container employed only slightly influenced the samples.     

One‐pot Green Synthesis of Pyrrole Derivatives Catalyzed by Nano Sulfated Zirconia as a Solid Acid Catalyst

A new and efficient method for the preparation of N‐substituted pyrroles from one‐pot Paal‐Knorr condensation has been accomplished using nano‐crystalline sulfated zirconia (SZ) as the catalyst in ethanol at moderate temperature. This new protocol has the advantages of easy availability, stability, reusability and eco‐friendliness of the catalyst, high to excellent yields, simple experimental and work‐up procedure. The synthesized compounds were confirmed through spectral characterization using IR, ¹H NMR, ¹³C NMR and mass spectra.     

Sol-Gel Preparation of Highly Active Sulfated Zirconia Supported by Alumina Catalysts

A series of sulfated mixed oxides of alumina and zirconia having a relative composition of 5% and 10% of ZrO₂ was prepared by means of sol-gel methods using zirconium propoxide or zirconium acetylacetone as precursor. The characterization of the physicochemical properties was carried out using ²⁷Al NMR, XRD, N₂ adsorption at 77 K, thermogravimetry, FTIR analysis of adsorbed pyridine, ²⁷Al NMR-MAS and XPS. The catalytic properties were studied by means of isomerization of n-hexane at 250°C. Results obtained allowed to propose that the use of Zr(acac)₄ as a zirconium precursor leads to a better retention of sulfate species which seems to form polymeric superficial sites. The symmetry of aluminium undergo an increase from tetrahedral to octahedral coordination and Zirconium atoms seems to be located in the second coordination sphere of Al. XRD analysis indicated an amorphous structure of obtained solids calcined at 650°C. The sulfated solids presented both Lewis and Brönsted acidic sites. Catalytic results showed that both activity and selectivity towards isomerization products were better using Zr (acac)₄ as precursor. Furthermore, the increase of the Zr loading affected considerably the catalytic properties of sulfated zirconia supported by alumina.     

Characterization of Sulfated Zirconias by DTA-TG and Drift Spectroscopy

Sulfated zirconias were prepared either by impregnation of zirconia with sulfuric acid or by a one step sol gel process by using different solvents. Solids prepared under closely similar conditions in different solvents show different amounts of sulfur and surface areas, thus demonstrating that the crystallization is different. Clear differences occur in the DTA-DTG curves with the appearance of a composite peak for the sol-gel catalysts, whereas the solid obtained by the classical two-step technique shows only one peak. The number of acid sites of these samples is changed by a factor of 3 depending on the preparation. Two types of hydroxyls are observed by infrared spectroscopy: one with bands at 3640 and 3585 cm^-1, associated with protons of moderate acidity, and a second at about 3300 cm^-1 able to exchange D with C₆D₆. Moreover, the infrared band of sulfates also contains two components: one at 1405 cm^-1 more intense for the most acidic solids and a second one at 1380 cm^-1. After activation, these solids are as active as zeolite beta for the acylation of anisole with acetic anhydride. This revised version was published online in July 2006 with corrections to the Cover Date.     

Direct Oxidation of Propylene with Molecular Oxygen over Ti-Modified Sulfated Zirconia Catalyst, 1. Characterization of the Catalyst and Catalytic Performances

Some zirconia-based catalysts were tested for the reaction of propylene in the presence of molecular O₂ without any additive at 428 K under atmospheric pressure. The catalyst TiSZ, which was prepared by a direct impregnation of titanium sulfate on amorphous zirconia, was found to show the highest yields of oxygenated compounds such as propylene oxide, with C4-C6 hydrocarbons. Characterization of the catalysts, by using XRD, XPS, and NH₃-TPD, exhibited that the catalytic performances were dependent on the surface acidity.     

Sulfated binary and trinary oxide solid superacids

A series of sulfated binary and trinary oxide solid superacids were prepared, and their catalytic activities for n-butane isomerization at low temperature were measured. The incorporation of different metal oxides into ZrO2 may produce a positive or negative effect on the acid strength and catalytic activity of the solid superacids. Sulfated oxides of Cr-Zr, Fe-Cr-Zr and Fe-V-Zr are 2 - 3 times more active than the reported sulfated Fe-Mn-Zr oxide. The enhancement in the superacidity and catalytic activity of these new solid superacids has been discussed on account of the results of various characteriation techniques.     

SO42−/ZrO2 上异丁烷重构化反应机理的原位核磁共振研究

 采用原位魔角旋转固体核磁共振技术研究了 2-13C-异丁烷在 SO42−/ZrO2 上的重构化反应机理, 考察了反应温度和 H2 气氛对反应的影响. 结果表明, 反应初期, 异丁烷在 SO42−/ZrO2 上的重构化反应以单分子机理为主, 之后向双分子机理转变; 反应温度的升高有利于单分子机理向双分子机理的转变; H2 的存在抑制了异丁烷的重构化反应, 特别对其双分子机理的反应有较强的抑制作用.     

氧化硅掺杂对硫酸化氧化锆酸性中心浓度和强度的提高

用氧化硅掺杂硫酸化氧化锆可以增强硫酸化氧化锆的酸性. 以413～453 K下甲醇液相脱水为模型反应考察了改进催化剂的性能. 结果表明,在掺杂和未掺杂氧化硅的硫酸化氧化锆催化剂上甲醇均相继脱水生成二甲醚和乙烯. 在掺杂了氧化硅的催化剂上还有一定量的丙烯生成,而未掺杂氧化硅的催化剂上则没有丙烯生成.