溶胶凝胶法制备PW/SiO_2负载型催化剂合成异丙基苯酚

用溶胶凝胶法制备出不同含量的磷钨酸负载到SiO2上的负载型催化剂。实验结果表明,该方法制备的催化剂对苯酚异丙醇合成异丙基苯酚有催化作用。采用氨程序升温脱附、X射线衍射对催化剂表面酸性、晶相进行表征。实验结果：不同含量的二氧化硅负载磷钨酸催化剂对苯酚转化率、异丙基苯酚的选择性有较大影响。当磷钨酸含量为SiO2的25%时苯酚转化率与异丙基苯酚选择性为最佳：分别为41.67%、62.86%。     

负载型WO3/SiO2-Al2O3催化剂用于合成乙酸乙酯反应研究

考察了SiO2、γ-Al2O3和SiO2-Al2O3载体负载氧化钨作为催化剂用于乙酸乙酯合成反应研究,并通过XRD、氮气物理吸附、Raman和NH3-TPD对催化剂进行表征。结果表明,氧化钨负载在SiO2-Al2O3载体上,具有更强的酸性和更高的酸量,有利于促进乙酸乙酯合成反应进行。当W在SiO2-Al2O3载体表面的负载量为8%(质量分数,下同)时,乙酸转化率最高可以达到69.7%,载体表面WO3晶体颗粒不利于提高酯化反应活性。     

还原温度对Ni-La2O3/SiO2-Al2O3催化剂加氢性能的影响

采用浸渍法制备Ni-La2O3/SiO2-Al2O3催化剂,对催化剂进行不同温度还原,并利用XRD、H2-TPR等表征,考察了还原温度对催化剂反应性能的影响.结果表明,低于400℃的还原条件下,NiO未被有效还原,催化剂表现出低的加氢活性;还原温度在450 ～ 550℃时,由于La2O3抑制了高温还原导致的活性组分Ni聚集长大,催化剂保持了高的加氢活性.     

H3PW6Mo6O40/SiO2催化合成苹果酯

以自制二氧化硅负载磷钨钼酸作催化剂,以乙酰乙酸乙酯和乙二醇为原料合成苹果酯,探讨二氧化硅负载磷钨钼酸对该反应的催化活性,较系统地研究了酯醇物质的量比、催化剂用量、反应时间等因素对产物收率的影响.实验表明:H3PW6Mo6O40/SiO2是合成苹果酯的良好催化剂,在n(乙酰乙酸乙酯)∶n(乙二醇)=1∶1.4,催化剂用量...     

H3PW12O40/SiO2催化合成糠醛乙二醇缩醛的研究

采用溶胶-凝胶法制备出具有Keggin结构的杂多酸H3PW12O40/SiO2复合催化剂,用FT-IR,XRD等手段表征了其结构形态。考察了复合催化剂催化合成糠醛乙二醇缩醛的工艺条件,其中重点考察了反应物配比、催化剂用量、反应时间及催化剂的重复使用性能等对产品收率的影响。结果表明:合成糠醛乙二醇缩醛的较优反应条件为:n(醛)/n(醇)=1.0/1.2,催化剂的用量为糠醛质量的6.0%,环己烷为带水剂,反应时间4.0 h。上述条件下,产物的收率可达85.0%以上。     

固载型杂多酸盐催化剂HPAS/TiO2-Al2O3的制备及催化性能研究

制备了固载型杂多酸盐催化剂HPAS/TiO2-Al2O3,用IR、XRD、TG-DTA等对催化剂进行了表征。在DOP的合成反应中考查了催化剂的催化作用。实验表明：HPAS/TiO2-Al2O3稳定性好,再生性能优良,是一种低温高效型催化剂。     

VOCs催化燃烧催化剂Mn/γ-Al2O3和CuMn/γ-Al2O3的性能研究

用浸渍法制备了两种负载型的Mn/g -Al2O3和Cu-Mn/g-Al2O3复合氧化物催化剂,同时用共沉淀法制备了Cu-Mn-O复合氧化物催化剂。以气相色谱为检测手段,用常压气体流动评价装置考察了这三种催化剂对苯、甲苯、二甲苯等挥发性有机化合物VOCs的催化燃烧性能。发现负载型的催化剂转化率达到99%时的反应温度比非负载型的降低30~40C,其中Cu-Mn/g-Al2O3催化剂具有更好的低温活性,催化燃烧反应的速率明显提高。负载型催化剂表面的活性组分以高度分散状态存在和催化剂高的比表面积是性能好的主要原因。     

H3PW12O40/SiO2催化合成环己酮乙二醇缩酮

采用溶胶-凝胶法制备了二氧化硅负载磷钨酸H3PW12O40/SiO2催化剂,并通过FTIR、XRD对其进行了表征。以环己酮和乙二醇为原料,合成了环己酮乙二醇缩酮,探讨了H3PW12O40/SiO2对缩酮反应的催化活性,考察了酮醇摩尔比、催化剂用量、带水剂用量、反应时间对产物收率的影响。结果表明,在n(环己酮)∶n(乙二醇)=1∶1.3,催化剂用量占反应物料总质量的1.2%,带水剂环己烷用量3 mL,反应时间45 min的最佳条件下,环己酮乙二醇缩酮收率可达89.7%。     

负载型杂多酸PW12／SiO2催化合成乙酸乙酯

以SiO2为载体,采用饱和浸渍法制备负载型杂多酸PW12／SiO2,用于催化合成乙酸乙酯。通过正交试验确定最佳反应条件为:催化剂用量为反应物总质量的4％,酸醇摩尔比为3,反应回流时间为120 min,酯化率可达91.56％以上。     

H3PW12O40-TiO2/SiO2超声光催化降解罗丹明B的研究

以硅胶为载体,采用浸渍法制备了H3PW12O40-TiO2/SiO2催化剂.通过对染料罗丹明B的超声光催化降解,探讨了催化剂的组成、用量、酸度、催化剂重复使用次数等因素对罗丹明B降解率的影响.结果表明:含4gH,PW12O40的TiO2溶胶浸渍在11gSiO2上的催化效果最佳.催化剂最佳用量为0.2g.初始罗丹明B溶液的pH为1时,反应速率最快.催化剂经活化处理后,重复使用6次,对罗丹明B的降解率仍达95.65%.相同条件下比较H3PW12O40-TiO2/SiO2和TiO2/SiO2对罗丹明B的降解效果发现,H2PW12O40可显著提高TiO2超声光催化降解罗丹明B的降解率.     

Effect of SiO2/Al2O3 ratio on the conversion of methanol to olefins over molecular sieve catalysts

A series of SAPO-34 molecular sieves with different SiO₂/Al₂O₃ ratios have been synthesized for the methanol-to-olefin (MTO) reaction. Their physico-chemical properties are characterized by various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and N₂ adsorption-desorption. The results are compared with those of the commercial HZSM-5, which show that the crystallinity and particle diameter of SAPO-34 as well as HZSM-5 increase with SiO₂/Al₂O₃ ratio. The variation of BET surface area of SAPO-34 is different from that of HZSM-5 and the sample with SiO₂/Al₂O₃ ratio of 0.4 exhibits the highest BET surface area. FT-IR spectra indicate that HZSM-5 has both Br?nsted and Lewis acid sites and Br?nsted acid sites are stronger, whereas SAPO-34 samples are dominated only by Lewis acid sites. When the SiO₂/Al₂O₃ ratio increases, propylene and butylenes become the predominant product of the MTO reaction over HZSM-5. In contrast, the main products of this reaction catalyzed by SAPO-34 are ethylene and propylene. According to the product distribution, the reaction mechanism over HZSM-5 catalysts is proposed.     

ZrO2/SiO2- and La2O3/Al2O3-supported platinum catalysts for CH4/CO2 reforming

Surface-phase ZrO₂ on SiO₂ (SZrOs) and surface-phase La₂O₃ on Al₂O₃ (SLaOs) were prepared with various loadings of ZrO₂ and La₂O₃, characterized and used as supports for preparing Pt/SZrOs and Pt/SLaOs catalysts. CH₄/CO₂ reforming over the Pt/SZrOs and Pt/SLaOs catalysts was examined and compared with Pt/Al₂O₃ and Pt/SiO₂ catalysts. CO₂ or CH₄ pulse reaction/adsorption analysis was employed to elucidate the effects of these surface-phase oxides.

The zirconia can be homogeneously dispersed on SiO₂ to form a stable surface-phase oxide. The lanthana cannot be spread well on Al₂O₃, but it forms a stable amorphous oxide with Al₂O₃. The Pt/SZrOs and Pt/SLaOs catalysts showed higher steady activity than did Pt/SiO₂ and Pt/Al₂O₃ by a factor of three to four. The Pt/SZrOs and Pt/SLaOs catalysts were also much more stable than the Pt/SiO₂ and Pt/Al₂O₃ catalysts for long stream time and for reforming temperatures above 700 °C. These findings were attributed to the activation of CO₂ adsorbed on the basic sites of SZrOs and SLaOs.     

柠檬酸引入方式对CoMo/TiO2-Al2O3催化剂加氢脱硫性能的影响

采用改进溶胶-凝胶法制备的TiO_2-Al_2O_3作复合载体,制备不同柠檬酸引入方式改性的CoMo/TiO_2-Al_2O_3加氢脱硫催化剂。利用低温N_2吸附-脱附、XRD、SEM和H_2-TPR等对催化剂进行表征,并采用固定床反应器对催化剂加氢脱硫性能进行评价。结果表明,后处理法制备的催化剂比表面积相对较大,孔道结构较好,活性金属组分以无定形形态均匀分散在载体表面,一定程度上减弱了其与载体间的相互作用;该催化剂可以延缓Co硫化,并且络合生成较多易于硫化还原的Mo物种,利于MoS_2在催化剂表面的堆叠,生成更多的Co-Mo-S(Ⅱ)活性相,因而相应的CoMo催化剂对噻吩加氢脱硫转化率显著提高。     

CoMo/MgO–Al2O3 supported catalysts: An alternative approach to prepare HDS catalysts

Three different supports were prepared with distinct magnesia–alumina ratio x = MgO/(MgO + Al₂O₃) = 0.01, 0.1 and 0.5. Synthesized supports were impregnated with Co and Mo salts by the incipient wetness method along with 1,2-cyclohexanediamine-N,N,N′,N′-tetraacetic acid (CyDTA) as chelating agent. Catalysts were characterized by BET surface area, Raman spectroscopy, SEM-EDX and HRTEM (STEM) spectroscopy techniques. The catalysts were evaluated for the thiophene hydrodesulfurization reaction and its activity results are discussed in terms of using chelating agent during the preparation of catalyst. A comparison of the activity between uncalcined and calcined catalysts was made and a higher activity was obtained with calcined MgO–Al₂O₃ supported catalysts. Two different MgO containing calcined catalysts were tested at micro-plant with industrial feedstocks of heavy Maya crude oil. The effect of support composition was observed for hydrodesulfurization (HDS), hydrodemetallization (HDM), hydrodeasphaltenization (HDAs) and hydrodenitrogenation (HDN) reactions, which were reported at temperature of 380 °C, pressure of 7 MPa and space-velocity of 1.0 h⁻¹ during 204 h of time-on-stream (TOS).     

SiO2/Al2O3对仿铜金属光泽釉面的性能影响

通过单因素实验探讨了SiO2/Al2O3摩尔比对仿铜金属釉的影响,研制了一种釉面耐磨性较高且呈现仿铜金属效果的生料金属釉。实验结果表明:随着SiO2/Al2O3摩尔比的增加,由于釉中析出的晶体种类和数量不同,从而导致釉面光泽度和色泽不一。当SiO2/Al2O3摩尔比为5.6时,釉中析出了CuMn2O4尖晶石晶体,从而使釉面呈现最佳的仿铜金属光泽,该釉面硬度为894.65Kg/mm2。     

微球形SiO2-Al2O3制备及其流化床蒽醌加氢性能研究

采用喷雾分散-油柱成型制备方法,以硅溶胶为硅源,制备不同含量SiO2掺杂改性的微球形氧化铝载体,研究SiO2含量对氧化铝载体结构及以其为载体的负载型催化剂性能的影响。研究表明,通过掺杂SiO2有效改善了氧化铝微球的热稳定性,且氧化铝载体的孔容、比表面积及酸中心数量均随SiO2含量的增加而增加,孔径随SiO2含量的增加而减小。Pd/SiO2-Al2O3催化剂结构表征及流化床蒽醌加氢性能评价结果表明,掺杂SiO2质量分数6%时,Pd/SiO2-Al2O3催化剂氢化效率大于12.5g·L^-1,选择性大于98.3%。     

纳米H3PW12O40／SiO2复合杂多酸催化合成琥珀酸二丁酯的研究

以纳米级H3PW12O4/MSiO2复合杂多酸为催化剂,琥珀酸和正丁醇为原料,甲苯为带水剂,合成琥珀酸二丁酯。实验结果表明,纳米H3PW12O40／SiO2复合杂多酸是合成琥珀酸二丁酯的良好催化剂,适宜的工艺合成条件为：琥珀酸用量为．1mol时,醇酸摩尔比为3．0：1．催化剂用量为琥珀酸总质量的2．0％,带水剂甲苯为10mL,回流温度下反应时间120min,此时酯化率可达99．3％。     

V2O5 catalysts supported on Al2O3–SiO2 mixed oxide: V, H MAS solid-state NMR, DRIFTS and methanol oxidation studies

Alumina–silica mixed oxide, synthesized by the sol–gel technique, was used as a support for dispersing and stabilizing the active vanadia phase. The catalysts were characterized employing ⁵¹V and ¹H solid-state MAS NMR, diffuse reflectance FT-IR, BET surface area measurements. The partial oxidation activities of the catalysts were tested using methanol oxidation as a model reaction. ⁵¹V solid-state NMR studies on the calcined catalysts showed the peaks corresponding to the presence of both tetrahedral and distorted octahedral vanadia species at low vanadia loadings and with an increase in V₂O₅ content, the ⁵¹V chemical shifts corresponding to amorphous V₂O₅ like phases were observed. DRIFTS studies of the catalysts indicated the vibrations corresponding tetrahedral vanadia species at low and medium loadings and at high V₂O₅ contents the vibrations corresponding V=O bonds of V₂O₅ agglomerates were observed. The V/Al–Si catalysts exhibited high selectivity for the dehydration product dimethyl ether in the methanol partial oxidation studies showing the predominance of the acidic nature of the alumina–silica support over the redox properties of the active vanadia phase.     

Influence of chlorine ions in Pt/A12O3 catalysts for methane total oxidation

Residual chlorine ions on a Pt/Al₂O₃ catalyst surface prepared from chlorine-containing precursors appear to inhibit the total oxidation of methane. At 450°C, as chlorine is eliminated with time on stream, the reaction rate increases despite the sintering of the platinum particles. The steady state reaction rate which is reached after 60 h is identical to that obtained with a catalyst prepared from a precursor containing no chlorine. Whether chlorine is present or not in the initial state of the catalyst does not appear to have an influence on the evolution of the platinum particle size.     

制备方法对Ni-Al_2O_3催化剂乙酰丙酸加氢性能的影响

分别采用浸渍法、沉积-沉淀法和共沉淀法制备了Ni-Al_2O_3催化剂,采用H2-TPR/TPD、XRD、NH3-TPD等对催化剂进行表征,并研究其催化乙酰丙酸加氢性能。结果表明,共沉淀法制备的催化剂中存在强的金属-载体相互作用、活性金属分散度高以及丰富的酸性中心。该催化剂表现出优异的催化乙酰丙酸加氢合成%-戊内酯性能以及高的使用稳定性。在160℃和4 MPa氢气压力反应条件下,乙酰丙酸转化率与%-戊内酯选择性可分别达85.0%和78.0%,催化剂循环使用3次时活性仍基本保持恒定。