表征固体超强酸性的新方法--正丁烷异构化反应的原位13C MAS NMR谱

室温下SO2 -4/ZrO2 催化剂 (SZ)上13 C标记的正丁烷异构化反应的原位13 CMASNMR谱研究结果表明 :其反应动力学符合Langmuir Hinshelwood一级可逆表面反应动力学公式 ,由该动力学公式计算得到的反应速率常数可以用于衡量固体催化剂的表面超强酸性 .这种新的表征方法显示采用一步 -醇热 -超临界干燥综合技术合成的SZ催化剂不仅比表面和硫酸根含量高 ,而且其超强酸性和异构化反应活性均明显优于常规法合成的催化剂 ,具有良好的应用前景 .     

用常温正丁烷异构化反应表征固体超强酸性

研究了室温下固体超强酸催化剂上正丁烷反应，发现转化率低于50％时，异构化选择性高于95％，正丁烷异构化反应动力学符合一级可逆反应规律，固体超强酸的酸强度与正丁烷异构化反应转化率和速率常数呈顺变关系，与反应表现活化能呈逆变关系．报出了一种新的表征固体超强酸性的实验方法．     

苯对Pt/Ga2O3/WO3/ZrO2 和Pd/Al2O3/ WO3/ZrO2催化剂上正己烷异构化反应的影响

研究了苯对Pt/Ga2O3/WO3/ZrO2 (PtGWZ)和Pd/Al2O3/ WO3/ZrO2(PdAWZ)催化剂上正己烷异构化反应的影响。结果表明,苯可影响PtGWZ和PdAWZ上正己烷异构化反应性能,苯含量越高影响越显著。与PdAWZ相比较,苯对PtGWZ上正己烷异构化反应的影响相对较小;苯对PtGWZ上正己烷异构化反应活性的影响是可逆的,撤除苯后PtGWZ对正己烷异构化的催化性能可完全恢复;苯对PtGWZ上正己烷异构化反应的稳定性没有影响。苯对PdAWZ上正己烷异构化反应活性的影响是不可逆的,PdAWZ用于含苯正己烷异构化反应催化剂会逐渐失活。热失重法积炭分析结果表明,相同条件下,含苯正己烷异构化反应后,PtGWZ上的积炭量较PdAWZ上的积炭量少。分析讨论了苯对PtGWZ和PdAWZ上正己烷异构化反应影响差异性的原因。     

Skeletal isomerization of 1-pentene

Series of ZSM-5 and Y zeolite catalysts have been prepared. Zeolites were submitted to ion exchange, drying, formation with 50 wt.% of aluminium hydroxide as a binder and then to final thermal treatment. Determination of catalysts activity in 1-pentene isomerization reaction was carried out in the temperature range of 175–325°C. The highest activity in isomerization reaction was attained in the presence of ZSM-5 zeolite catalysts with strong and medium strength acidity.     

钨基催化剂上烷烃异构化研究进展

随着人们对汽油质量的要求越来越高,烷烃异构化越来越受到重视,尤其是长链烷烃异构化,因此研究高性能的异构化催化剂具有非常重要的意义。本文综述了一类用于长链烷烃异构化的新型催化剂-钨基催化剂的研究进展,介绍了此类催化剂的制备、异构化反应,简要介绍了其反应机理。并分析了此类催化剂今后的发展趋向和应用前景。     

Skeletal Isomerization of <Emphasis Type="Italic">n</Emphasis>-butenes over Solid Acid Catalysts

Conversion reactions of n-butenes over zeolites and amorphous catalysts have been investigated to deduce the factor that determines the selectivity for the skeletal isomerization producing isobutene. The effects of pore structure and acid site concentration on the selectivity for the skeletal isomerization are discussed on various catalysts. The pore structures of FER and CLI zeolites induce the distant locations of butene molecules, accelerating monomolecular skeletal isomerization. On the other hand, acid site concentration determines the preferred reaction path of n-butenes on amorphous catalysts. Oligomerization followed by cracking that produces various hydrocarbons is suppressed on the catalyst with low acid site concentration, resulting in high selectivity for isobutene. The feasibility of monomolecular skeletal isomerization on zeolites and amorphous catalysts is confirmed by its reversibility with high selectivity.     

磷钨杂多酸及其铯盐上的常温正戊烷异构化反应

制备了一系列用于正戊烷异构化的磷钨杂多酸及其铯盐催化剂,并对它们进行了详细的物性表征。实验结果表明, Cs含量对催化剂的比表面、孔结构、热稳定性和表面酸量有显著的影响。考察了所制备的催化剂上常温下正戊烷异构化反应的活性和选择性。利用催化剂表征结果讨论了活化温度和Cs含量等因素对催化性能的影响。磷钨杂多酸及其铯酸式盐属固体超强酸。根据35℃时正戊烷异构化反应速率常数估测H~3PW~1~2O~4~0和Cs~2~.~2~5H~0~.~7~5PW~1~2O~4~0的酸强度H~0约在-13～-12.4之间。     

New selectivities from old catalysts. Occlusion of Grubbs’ catalysts in PDMS to change their reactions

This article describes new selectivities for Grubbs’ first and second generation catalysts when occluded in a hydrophobic matrix of polydimethylsiloxane (PDMS). Occlusion of catalysts in mm-sized slabs of PDMS is accomplished by swelling with methylene chloride then removing the solvent under vacuum. The catalysts are homogenously dissolved in PDMS yet remain catalytically active. Many substrates that react by olefin metathesis with Grubbs’ catalysts freely dissolved in methylene chloride also react by olefin isomerization with occluded catalysts. Eleven examples of substrates that exhibit dual reactivity by undergoing olefin isomerization with occluded catalysts and olefin metathesis with catalysts dissolved in methylene chloride are reported. Most of these substrates have olefins with allylic phosphine oxides, carbonyls, or ethers. Control experiments demonstrate that isomerization is occurring in the solvent by decomposition of the catalyst from a ruthenium carbene to a proposed ruthenium hydride. This work was extended by heating occluded Grubbs’ first generation catalyst to 100 °C in 90% MeOH in H₂O in the presence of various alkenes to transform the Grubbs’ catalyst into an isomerization catalyst for unfunctionalized olefins. This work demonstrates that occlusion of organometallic catalysts in PDMS has important implications for their reactions and can be used as a method to control which reactions they catalyze.     

Bifunctional hydrogen-bond donors that bear a quinazoline or benzothiadiazine skeleton for asymmetric organocatalysis

Hydrogen-bond (HB)-donor catalysts that bear a 2-aminoquinazolin-4-(1H)-one or a 3-aminobenzothiadiazine-1,1-dioxide skeleton have been developed, and it has been shown that these catalyst motifs act similarly to other HB-donor catalysts such as thioureas. The highly enantioselective hydrazination of 1,3-dicarbonyl compounds was realized even at room temperature with up to 96% ee for 2-aminoquinazolin-4-(1H)-one-type catalysts, which were more effective than the corresponding urea and thiourea catalysts. In addition, benzothiadiazine-1,1-dioxide-type catalysts were shown to promote the isomerization of alkynoates to allenoates with high enantioselectivity. To overcome the problem that the products were obtained as mixtures with the starting alkynoates, we developed the tandem isomerization and cycloaddition of alkynoates for the synthesis of advanced chiral compounds such as bicyclo[2.2.1]heptenes and 3-alkylidene pyrrolidine without a significant loss of enantioselectivity.     

羟基磷灰石负载HRh(CO)(TPPTS)3催化1-己烯氢甲酰化反应高选择性和特殊的异构化功能

采用浸渍法制备了以羟基磷灰石(HAP)载型水溶性铑络合物HRh(CO)(TPPTS)3/HAP催化剂(TPPTS=三苯基膦三间磺酸钠), 采用傅里叶变换红外光谱(FTIR)、 固体核磁共振波谱(31P CP-MAS NMR)、 扫描电子显微镜(SEM)、 电感耦合等离子发射光谱(ICP-OES)和比表面积测定(BET)等对催化剂进行了表征. 该催化剂在催化1-己烯氢甲酰化反应中表现出高活性和高选择性, 在优化条件下获得了100%的醛选择性和高转化频率(TOF=2465 h-1). 该催化剂还对1-己烯、 2-己烯和3-己烯表现出特殊的异构化功能. 该催化剂制备方法简单, 通过简单离心分离可以循环使用. 对HAP负载HRh(CO)(TPPTS)3的原理以及催化剂对烯烃异构化的机理进行了探讨.     

碳化钨负载S2O8^2-/ZrO2固体超强酸催化剂上的正戊烷反应研究

首次研究了碳化钨负载S2O8^2-/ZrO2(PSZ)固体超强酸催化剂(WC/PSZ)上正戊 烷的反应情况及影响催化剂活性的各种因素，并用GC-MS，XRD，BET等手段分析了 正戊烷反应产物和催化剂的物理化学性质等。结果表明：WC/PSZ对正戊烷具有异构 化和裂解的双重催化作用。PSZ在负载适量碳化钨后对正戊烷反应的活性和选择性 显著提高，显示出优于Pt／PSZ催化剂的效果，碳化钨的负载量为20％的效果最佳 。适当的焙烧、活化和反应温度等条件是取得良好反应效果的关键。     

On the Epimerization of endo-Dicyclopentadiene during Terpolymerization with Ethylene and Propylene

The isomerization of endo-DCP (I) to exo-DCP (II) during the synthesis of EPDM with several Ziegler-Natta catalysts has been investigated by means of IR spectroscopy and by reference to EPDM containing different levels of true exo-DCP. The I - II epimerization was absent for ail the catalysts examined. Only with the systems VC1₄-Et₂AlCl was a trace of isomerization observed, and then only at the limit of sensitivity of the analytical method. No isomerization was detected via gas-chromatographic analysis in monomeric DCP recovered from the polymerization mixture. Ziegler-Natta catalysts having acidic character can homopolymerize I, but epimerization was observed only with the system voc1₃-Et₃Al₂Cl₃. The results obtained have been interpreted in terms of a terpolymerization mechanism having a prevalent coordinated character. The poly functionality of Ziegler-Natta catalysts is sometimes responsible of the secondary isomerization process.     

改性纳米ZSM-5催化剂上正辛烷转化反应的研究

以纳米晶粒HZSM-5(20~50 nm)沸石为活性组分, 用碱性介质水热处理、 负载混合稀土和ZnO(或GaO)组合改性方法对纳米HZSM 5分子筛进行改性, 并用TEM， XRF， IR及XRD等手段对催化剂进行表征. 以正辛烷的芳构化和异构化为模型反应, 研究了改性纳米ZSM 5催化剂总酸和酸强度分布、 L/B酸位比例对正辛烷异构化和芳构化反应性能的影响以及催化剂酸强度、 L/B酸位比例与催化剂稳定性和积炭的关系. 结果表明, 碱性介质水热处理和混合稀土改性后, 总酸量减少和酸强度降低导致纳米HZSM-5催化剂的芳构化活性减弱, 异构化活性增强, 稳定性明显提高. 在碱性介质水热处理和负载混合稀土改性的基础上, 再负载适量氧化锌(或氧化镓)改性的催化剂， 总酸量增加, 强酸中心数量减少, B酸略有减少, 而L酸明显增加, L/B酸位比值增加. L酸中心和B酸中心的协同作用和较合适的L/B(1.4~1.7)比值使改性的纳米ZSM-5催化剂保持了较强的和稳定的芳构化和异构化活性, 催化剂积炭失活速率降低. 芳烃和异构烷烃产率分别达到约50%和30%, 高辛烷值的烷基芳烃(C7~C9)和异构烷烃(C4~C6)的选择性分别达到84%和80%.     

膦化聚2,6—二甲基1,4—苯醚负载钯催化剂的表征及其催化性能

报道了四种不同P/Pd摩尔比的膦化聚2,6-二甲基1,4-苯醚负载把催化剂的加氢和异构化性能;通过XPS、电镜和远红外对催化剂进行了表征;并考察了溶剂和温度对催化剂活性的影响.     

正戊烷异构化反应表征固体超强酸性

详细研究了低温下固体酸催化剂上的正戊烷反应，发现在ＳＯ４＾２－／ＭｘＯｙ型固体超强酸，ＨＭ和ＨＺＳＭ－５沸石表面上正戊烷反应以异构化为主，其反应动力学符合一级可逆反应规律，催化剂的酸强度与正戊烷异构化反应速率常数呈顺变关系，由此提出了一种适合于－１６＜Ｈ０＜－１２的固体酸强度测定方法，解决了该区域内有色样品或高温易分解样品在酸性测量上的难题。     

碳化钨负载S2O8^2-/ZrO2固体超强酸催化剂上的正戊烷反应研究

首次研究了碳化钨负载S2 O2 -8 ZrO2 (PSZ)固体超强酸催化剂 (WC PSZ)上正戊烷的反应情况及影响催化剂活性的各种因素 ,并用GC MS ,XRD ,BET等手段分析了正戊烷反应产物和催化剂的物理化学性质等 .结果表明 :WC PSZ对正戊烷具有异构化和裂解的双重催化作用 .PSZ在负载适量碳化钨后对正戊烷反应的活性和选择性显著提高 ,显示出优于Pt PSZ催化剂的效果 ,碳化钨的负载量为 2 0 %的效果最佳 .适当的焙烧、活化和反应温度等条件是取得良好反应效果的关键     

Comparison of the promoting effects of gallium and aluminium on the n-butane isomerization actvity of sulfated zirconia

Sulfated zirconia catalysts promoted by gallium or aluminium were prepared and tested for n-butane isomerization. Both elements increase and stabilize the isomerization rate. Characterization results showed that the promoting mechanism of gallium was different from that of aluminium. This revised version was published online in June 2006 with corrections to the Cover Date.     

SO42-/ZrO2-Al2O3催化剂表面酸性质对正丁烷异构化反应性能的影响研究

采用“沉淀-浸渍”法制备一系列不同硫酸负载量的SO₄^2-/ZrO₂-Al₂O₃催化剂,利用N₂吸附-脱附、Py-FTIR、XRD等手段对催化剂进行表征。在常压、200 ℃、H₂：C₄=2：3和质量空速为3 h^-1的反应条件下,在固定床微型反应评价装置上考察了硫酸负载量对SO₄^2-/ZrO₂-Al₂O₃催化正丁烷异构化反应性能的影响。Py-FTIR结果表明,硫酸化处理为催化剂表面提供了丰富的Brønsted酸性位,其中,强Brønsted酸性位在正丁烷异构化反应中起重要作用,因此,硫酸化处理可显著提高正丁烷异构化活性,而Lewis酸性位与之没有直接关系。     

Influence of Mg/Al Molar Ratio on the Structures and Properties of Ru-Mg Alx Catalysts for Isomerization Linoleic Acid

With the knowledge on the significant effect of basic site and Ru on the catalytic performance of heterogeneous catalysts in the isomerization of linoleic acid to conjugated linoleic acid,a series of Ru-Mg Alx compounds with different basicity have been prepared by controlling the Mg/Al molar ratio. The results showed the catalysts with different basicity markedly influence the structure,the Ru dispersion,properties and catalytic performances for the isomerization reaction. The strong basic site is conductive to the high yield of CLA products. The strong basic site and the well-dispersion RuO_2 synergetic catalysis for the isomerization reaction,basic site and the well-dispersion RuO_2 synergetic effect are possibly via a Mg-O-Ru linkage.     

Catalytic activity and acidity of Al pillared clays and zeolites in different hydrocarbon reactions

In comparison with zeolites, a variety of Al pillared clays did not prove as promising cracking catalysts, possibly because their Br?nsted sites are hidden. In the less demanding double bond shift isomerization, both catalyst types were comparable probably due to the presence of Lewis sites on both catalysts.