高分散隔离活性位催化剂中过渡金属离子结构对丙烷选择氧化反应性能的影响

考察了碱金属K修饰的SiO2负载极低含量过渡金属的高分散隔离活性位系列催化剂(K-M/SiO2(n(K)∶n(M)∶n(Si)=10∶1∶1000),M=V,Cr,Mn,Fe,Co,Ni,Cu,Zn)的丙烷选择氧化催化性能,并运用UV-Raman和CO2-TPD等方法,对该系列催化剂进行了结构和物化性能表征,探讨了催化剂的表面离子结构与催化反应性能之间的关系。 发现钾修饰的SiO2负载过渡金属高分散隔离活性位催化剂上过渡金属离子的组态结构,对丙烷选择氧化反应性能有重要影响。相对稳定的全充满或无d电子的表面离子结构有利于选择氧化反应进行,而存在多种价态的相对不稳定的离子结构有利于深度氧化的进行。 这一离子结构与丙烷选择氧化催化性能的关系与前期乙烷选择氧化规律相似,进一步说明在高分散隔离活性位催化剂中,过渡金属离子的电子组态结构是影响低碳烷烃选择氧化反应性能的最重要因素。     

Highly active Mo-V-Te-Nb-O catalysts obtained by eliminating surface Te0 for selective oxidation of propane to acrylic acid

Different methods were used to eliminate the negative effect of surface Te⁰ in Mo-V-Te-Nb-O catalysts. The characterization and catalytic results showed that the best catalytic performance was obtained on the catalyst prepared by addition of HNO₃, and the excellent catalytic behavior could be attributed to the elimination of surface Te⁰ and the optimum synergetic effect between the M1 and M2 phases.     

Synthesis of Pt-SnOx/TS-1@SBA-16 Composites and Their High Catalytic Performance for Propane Dehydrogenation

A novel composite material of TS-1@SBA-16 was synthesized by enwrapping TS-1 zeolite crystals with mesoporous SBA-16 silica. This composite was used as catalyst support for loading Pt-SnOx in the propane dehydr genation(PDH) reaction. Catalysts were characterized by means ofN2 adsorption-desorption, XRD, SEM, TEM, XPS, UV-Vis, and Raman spectroscopy. The effect of different contents of TS-1 on PDH was investigated, and the optimal amount of TS-1 was determined to be 10%. The catalyst with TS-1 content of 10% showed the highest PDH activity and the initial conversion of propane over it can achieve 54.5%, higher than those over TS-1 or SB A-16-supported ones. The superior catalytic performance of Pt-SnOx/TS-1 @SBA-16 is related to the synergistic effect of the excellent mass transfer performance through the hierarchical porous structure, suitable acid acidity and electronic effect of Ti species.     

Effective VTeO/SBA-15 Catalyst Prepared by Precursor Method for the Selective Oxidation of Propane to Acrolein

Precursor decomposition was used for the preparation of VTeO/SBA-15 catalyst for the selective oxidation of propane to acrolein. The catalyst shows a better performance compared with those prepared by conventional impregnant method. A yield of 9.3% of acrolein was achieved with 2% V loadings at 500 ℃. XRD, N2-adsorption, H2-TPR, Py-IR and XPS measurements were used to unclose the relationship between the structure and performance of the catalyst.     

Propane phosphonic acid anhydride: a new promoter for the one-pot Biginelli synthesis of 3,4-dihydropyrimidin-2(1H)-ones

Propane phosphonic acid anhydride has been found to promote the Biginelli synthesis of 3,4-dihydropyrimidin-2(1H)-ones. The use of this agent is characterized by moderate costs, low toxicity and simple workup conditions.     

Propylene/propane mixture adsorption on faujasite sorbents

The adsorption of propylene and propane on zeolite NaX with and without a saturated (36 wt%) amount of CuCl have been investigated. The single component adsorption isotherms could be well described with a Dual-Site Langmuir model. The dispersion of CuCl results in a decrease of the maximum adsorption capacity of the zeolite for both components. For propylene a strong adsorption via π-complexation with CuCl is present, increasing the adsorption selectivity of the zeolite. The binary mixture (50:50) adsorption was determined via breakthrough/desorption experiments at 318, 358 and 408 K with a partial pressure of the two components between 0.8–54 kPa. For NaX the mixture loading could be well described with the IAS-theory and the single component isotherms, both qualitatively and quantitatively. A transition from an enthalpy controlled adsorption at lower loadings to an entropy affected adsorption at higher loadings was observed. The IAS-theory could only qualitatively describe the trends in the observed mixture adsorption for the CuCl/NaX adsorbent. The dispersion of CuCl in NaX results in a modest improvement of the adsorption selectivity for propylene over propane (from 3–7 to 15–30) but at the expense of a reduced capacity.     

Dehydrogenation of propane to propene over phosphorus-modified HZSM-5 supported Ga2O3

Dehydrogenation of propane to propene in the presence of CO₂ was investigated over gallium oxide catalysts supported on phosphorus-modified HZSM-5. The stability of the catalyst improves with an increase in P-loading, due to the decrease in the acid strength and number of strong acid sites of the catalyst.     

丙烷选择氧化催化剂AgMoO2PO4*MoO3活性表面结构研究

丙烷选择氧化制丙烯、丙烯醛 (酸 )是低碳烷烃优化利用的重要催化课题 .这类反应中烷烃的高效活化和定向转化很难兼得 .阐明有关催化剂的体相和活性表面结构具有重要意义[1～ 3] .由于受原位实验技术的限制 ,相关研究较少 [4 ,5] .本文采用原位共焦显微拉曼光谱、XRD及 XPS技术考察了丙烷选择氧化催化剂 Ag Mo O2 PO4 · Mo O3的活性表面结构 .1　实验部分1 .1　催化剂的制备　Ag Mo O2 PO4 ·Mo O3以 Ag2 O,Mo O3和 (NH4 ) H2 PO4 粉末为原料 ,采用湿混合法制备 :将上述原料加入适量的去离子水充分混合 ,在 1 1 0℃烘干 ,在 55…     

Cr/NaZSM-5催化剂上CO2氧化丙烷脱氢反应

以亚微米级NaZSM-5为载体合成了一系列负载型Cr催化剂, 采用氮气吸附、 XRD、 UV-Vis和H2-TPR对Cr/NaZSM-5催化剂的结构和织构性质进行了表征, 并评价了催化剂在CO2气氛下的丙烷脱氢性能. 硅铝摩尔比为60, Cr质量分数为3%的催化剂具有最高的反应活性, 于550 ℃反应10 min和8 h后的丙烷转化率分别为48.3%和30.1%, 丙烯选择性则分别为86.0%和91.8%. 催化剂中的Cr6+含量和反应初活性具有良好的对应关系, 表明高Cr6+含量对催化剂表现出高的丙烷脱氢活性是至关重要的. CO2气氛下的丙烯产率明显比氮气气氛下的高, 这是由于CO2气氛下催化剂表面有较多量的Cr6+, 并且CO2可通过逆水煤气变换反应除去脱氢反应生成的氢.     

Vapour pressure and excess Gibbs free energy of binary mixtures of hydrogen sulphide with ethane, propane, and n-butane at temperature of 182.33 K

The vapour pressure of binary mixtures of hydrogen sulphide with ethane, propane, and n-butane was measured at T = 182.33 K covering most of the composition range. The excess Gibbs free energy of these mixtures has been derived from the measurements made. For the equimolar mixtures for (H₂S + C₂H₆), (820.1 ± 2.4) J · mol⁻¹ for (H₂S + C₃H₈), and (818.6 ± 0.9) J · mol⁻¹ for (H₂S + n-C₄H₁₀). The binary mixtures of H₂S with ethane and with propane exhibit azeotropes, but that with n-butane does not.