空心微球氧化铝负载Pt-In催化异丁烷脱氢研究

针对异丁烷脱氢催化剂存在容易烧结与积碳的问题,开发了采用水热法制备的2种不同形貌的Al₂O₃载体,将其负载Pt-In获得的催化剂用于异丁烷脱氢反应中,研究其对异丁烷脱氢催化行为的影响。借助XRD、SEM、TEM、NH₃-TPD、XPS、TG-DTA及低温N₂吸-脱附法对催化剂进行物化性能研究。结果表明:由纳米片构建的多孔空心微球氧化铝负载Pt-In催化剂具有较小的Pt纳米粒子、低的比表面积、强的Pt-In相互作用、高的In³⁺/In⁰比例且缺少强酸位,从而获得优异的异丁烷脱氢性能,其异丁烯选择性和产率高达93.5%和40.3%,同时异丁烷转化率可稳定在43.0%,反应后的金属颗粒无聚集烧结现象,表现出优异的抗烧结和积碳性能。     

异丁烷催化脱氢反应机理与失活动力学研究进展

异丁烯是化工行业重要的基础原料,国内外对异丁烯的需求量逐年递增。仅靠石油催化裂解已无法满足对异丁烯的需求,开展异丁烷脱氢制异丁烯工艺的研究备受关注。综述Cr系异丁烷脱氢催化剂的研究进展,探讨Cr系催化剂的活性中心以及发生在活性中心上的多种反应机理和相应的动力学模型,详述催化剂的失活机理,总结积炭的形成过程,指出Cr系异丁烷催化脱氢反应和失活机理以及相关动力学方面研究的不足,并对未来研究前景进行展望。     

改性VOx/MSU-1催化剂上CO2氧化异丁烷脱氢反应

以MSU-1为载体制备了一系列改性的VOx/MSU-1催化剂,并在CO2氧化异丁烷脱氢制异丁烯的反应中评价了催化剂的性能,发现稀土元素La、Ce的加入能提高催化剂的活性。采用XRD、H2-TPR及NH3-TPD方法对催化剂La2O3-VOx/MSU-1进行了深入的表征,发现La2O3的加入提高了载体MSU-1上活性组分VOx的分散度,同时也改善了催化剂表面的酸碱性,更加有利于异丁烷氧化脱氢反应的进行。优化了反应条件,在最佳反应条件下,异丁烷的转化率为63.6%,异丁烯的产率为52.3%。最后,通过8 h的稳定性实验,发现与VOx/MSU-1相比,催化剂La2O3-VOx/MSU-1具有更好的催化稳定性。     

钒基MSU-1催化剂上二氧化碳氧化异丁烷脱氢反应条件的优化研究

以介孔材料MSU-1为载体,不同金属氧化物为活性组分,分别制备负载型催化剂并研究其在CO<,2>气氛中异丁烷脱氢的催化活性.结果证明VOx/MSU-1催化剂有最好的异丁烷氧化脱氢催化活性.基于此,对影响CO<,2>氧化异丁烷脱氢的温度、空速和氧烷比等工艺条件进行了考察,结果显示,当温度为853 K,空速为7200 mL...     

Dehydrogenation and Isomerization of n-Butane or Isobutane Over Cr Catalysts Supported on Zeolites

Dehydrogenation and isomerization of n-butane or isobutane into isobutene over Cr catalysts supported on zeolites were investigated. We found that Cr catalyst supported on H-SSZ-35-type zeolite, having one-dimensional cage-type channel structure, was very effective for this reaction and the yield of isobutene was 5.44% from n-butane and 9.57% from isobutane. In this reaction, it is suggested that dehydrogenation of butanes is accelerated by Cr₂O₃ loading, and solid acidity of the zeolite support favors isomerization.     

新型异丁烷脱氢催化剂性能

对异丁烷脱氢催化剂YBD-101和国外某催化剂L进行性能比较。采用XRD和BET研究催化剂的物相结构和比表面积,固定床反应器考察两种催化剂的异丁烷脱氢催化活性和产物选择性。结果表明,催化剂YBD-101较催化剂L具有Cr2O3颗粒细小和比表面积大等特点。在反应温度(500~620)℃和空速(1.0~2.0)h-1条件下,催化剂YBD-101的异丁烷转化率高于催化剂L8个百分点,产物选择性高于催化剂L 3个百分点。催化剂YBD-101的活性稳定性优于催化剂L,再生周期明显延长,具有较好的经济效益和社会效益。     

异丁烷脱氢制异丁烯反应过程Pt-Sn-K/γ-Al2O3催化剂的失活分析

研究了Pt-Sn-K/γ-Al₂O₃催化剂在异丁烷脱氢-器内再生循环过程中脱氢反应性能,采用N₂物理吸附、CO脉冲吸附、NH₃-TPD和TG对催化剂进行表征,提出了催化剂的失活原因。结果表明,新鲜Pt-Sn-K/γ-Al₂O₃催化剂上异丁烯初始收率为39.5%,脱氢反应24 h后异丁烯收率降至20.6%。经2次脱氢-再生循环后,催化剂上异丁烯收率降至11.1%,72 h反应结束时异丁烯收率降至7.9%。积炭覆盖催化剂的活性位是导致催化剂失活的主要原因。Pt烧结及Pt-Sn合金形成使催化剂上Pt分散度降低,导致再生后催化剂活性明显下降。     

K_2O-CuO-Cr_2O_3/Al_2O_3催化剂上异丁烷脱氢制异丁烯的催化性能研究

以Cr2O3为活性组分,K2O和CuO为助剂,γ-Al2O3为载体制备负载型催化剂,并考察了其对异丁烷直接脱氢制异丁烯的催化活性。探讨了活性组分Cr2O3及助剂K2O、CuO对催化剂活性的影响,结果表明,金属Cr含量与催化活性直接相关,K对催化剂选择性有改进作用。实验结果还表明了该催化剂适用于高空速下的催化反应。对含不同助剂的Cr系催化剂进行了N2吸附-脱附、XRD等表征。N2吸附-脱附发现催化剂比表面积与异丁烷脱氢的初始活性存在一定的对应关系;XRD的表征说明各组分能很好地分散负载在载体上;其中,在优化的反应条件温度853 K、空速1000 h-1下,K2O-CuO-Cr2O3/Al2O3催化剂有最佳的异丁烷的转化率和异丁烯的收率,分别达64.76%和57.24%。     

K2O-CuO-Cr2O3/Al2O3催化剂上异丁烷脱氢制异丁烯的催化性能研究

以Cr2O3为活性组分,K2O和CuO为助剂,γ-Al2O3为载体制备负载型催化剂,并考察了其对异丁烷直接脱氢制异丁烯的催化活性.探讨了活性组分Cr2O3及助剂K2O、CuO对催化剂活性的影响,结果表明,金属Cr含量与催化活性直接相关,K对催化剂选择性有改进作用.实验结果还表明了该催化剂适用于高空速下的催化反应.对含不...     

Fe掺杂对Pt-Sn-K/γ-Al_2O_3异丁烷脱氢催化剂性能的影响

采用共沉淀法制备不同Fe含量的Fe(x)-γ-Al_2O_3复合氧化物载体,并采用真空浸渍法制备了Pt-Sn-K/Fe(x)-γ-Al_2O_3催化剂。对制备的催化剂进行XRD、N_2物理吸附-脱附和NH_3-TPD表征,研究Fe的掺杂对Pt-Sn-K/Fe(x)-γ-Al_2O_3催化剂的结构及其催化异丁烷脱氢反应性能的影响。结果表明,Fe的引入可以改变催化剂的反应活性和产物选择性,当Fe_2O_3掺杂质量分数为4%时,催化剂具有最高的异丁烯收率,50 h的平均收率达到42.9%。     

Surface organometallic chemistry on metals in water: Chemical modification of platinum catalyst surface by reaction with hydrosoluble organotin complexes: application to the selective dehydrogenation of isobutane to isobutene

Surface organo-metallic chemistry on metals can be a new route to generate supported bimetallic catalysts. According to previous works on Pt–Sn catalysts, the reaction of tetra n-butyl-tin on the reduced platinum surface leads to well-defined bimetallic catalysts which are very active and selective in the dehydrogenation of isobutane into isobutene. The presence of tin not only isolates the surface platinum atoms from each other (EXAFS) and thus prevents a fast deactivation by decreasing the processes of C–C bond cleavage but also favors the regeneration processes under air. So far the catalyst preparations were carried out either in the gas phase or in organic solution (e.g. heptane). However, in order to meet the industrial criteria of process simplicity, there is a need to carry out such catalyst preparation in water.

In this work, Pt–Sn/Al₂O₃ and Pt–Sn/SiO₂ catalysts was prepared by reacting tris n-butyl-tin hydroxide on the platinum surface, in water solution under atmospheric pressure of hydrogen. The kinetics of the reaction was followed by measuring the amount of butane evolved as a function of time. The solids obtained were characterized by CO, O₂ or H₂ chemisorption and electron microscopy (CTEM and EDAX). Clearly, the (n-Bu)₃Sn(OH) reacts selectively on the platinum surface and not with the support, with evolution of butane, leading to a bimetallic catalyst where the platinum atoms are isolated from each other by the tin atoms. Very high selectivities (>95%) and activities were obtained for the reaction of isobutane dehydrogenation into isobutene and it was concluded that surface organo-metallic chemistry on metal in water can be an alternative route to prepare well-defined supported bimetallic Pt–Sn catalysts.     

Activity of vanadium magnesium oxide supported catalysts in the dehydrogenation of isobutane

The activity of the vanadium magnesium binary oxides supported on C_act, SiO₂, γ-Al₂O₃ and ZnO in the dehydrogenation of isobutane to isobutene under the carbon dioxide or inert gas atmosphere was investigated. The highest isobutene yield (34.8%) was obtained over active carbon supported catalyst. The role of carbon dioxide in the dehydrogenation process was determined on the basis of additional tests: the RWGS reaction, gasification of coke and regeneration of partially reduced catalysts. The temperature-programmed techniques (TPR-H₂, TPD-NH₃ and TPD-CO₂) were used to characterize the catalysts.     

原料中杂质对异丁烷脱氢Pt-Sn-K/Al2O3催化剂性能的影响

采用固定床法考察了原料异丁烷中乙硫醇、甲醇、正丁烷和1-丁烯等杂质对Pt-Sn-K/Al₂O₃催化剂上异丁烷脱氢制异丁烯反应性能影响,反应产物使用气相色谱进行分析.实验结果表明,在异丁烷脱氢制异丁烯正常反应条件下,即温度580℃、压力0.1MPa、进料组成H₂/i-C₄H₁₀(体积比)= 2、总空速GHSV = 2000h^-1、GHSV(i-C4H10)= 667h^-1,乙硫醇、甲醇、正丁烷和1-丁烯对Pt-Sn-K/Al₂O₃催化剂的异丁烷转化率和异丁烯选择性均有较大的影响,且杂质含量越高,对催化剂的转化率和选择性影响越大.并对杂质造成催化剂失活的原因进行了分析.     

助剂硼对K2O-Cr2O3/γ-Al2O3催化剂异丁烷脱氢性能的影响

采用等体积浸渍法制备了硼改性的K₂O负载量2%、Cr₂O₃负载量12%的不同硼负载量的K₂O-Cr₂O₃-B₂O₃/γ-Al₂O₃催化剂,在560℃、异丁烷空速400h-1、常压的条件下在固定床反应器中考察了催化剂的异丁烷脱氢性能,并对载体及催化剂进行了BET、XRD、NH₃-TPD和O₂-TPO等表征。结果表明:助剂硼的加入对催化剂结构无明显影响,但可以有效调节催化剂的表面酸性,从而减少裂解和积炭等不良反应的发生,提高催化剂的异丁烯选择性和稳定性;硼负载量过高会导致活性组分Cr₂O₃的聚集,影响活性组分的分散,导致催化剂上异丁烷转化率降低;综合考虑催化剂的活性、稳定性和异丁烯选择性,硼负载量为1.0%左右较为适宜。     

Oxidative dehydrogenation of isobutane over magnesium molybdate catalysts

A series of Mo-Mg-O catalysts with different crystalline phases (pure and mixtures) have been studied in the oxidative dehydrogenation of isobutane. X-ray diffraction, UV–Vis spectroscopy and temperature programmed reduction were applied to characterise the samples. In addition, the kinetics of the lattice oxygen exchange with labelled C¹⁸O₂ was measured for all samples. It has been found that the MgMoO₄ phase contains the surface active sites suitable for the adsorption of isobutane and for its dehydrogenation to isobutene with the minimum of cracking reaction. Moreover, for this reaction the migration of lattice oxygen ions is not a key parameter in the control of the catalytic properties of these materials.     

Dehydrogenation of isobutane over Sn/Pt/Na-ZSM-5 catalysts: The effect of SiO<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> ratio,amount and distribution of Pt nanoparticles on the catalytic behavior

Sn/Pt/Na-ZSM-5 was used as catalyst for the dehydrogenation of isobutane, and the effect of SiO₂/Al₂O₃ ratio and the dispersion of Pt nanoparticles on the conversion and product selectivity were studied under atmospheric pressure at 848 K. The catalysts were characterized by various techniques such as H₂ chemisorption, TEM, SEM, EDX, XRD, FT-IR, TG/DTG, elemental analysis by XRF and ICP techniques. Higher dispersion of Pt nanoparticles in the catalyst with SiO₂/Al₂O₃ ratio of 40 resulted in higher selectivity for isobutene.     

Effect of calcination temperature on isobutane dehydrogenation over Mo/MgAl2O4 catalysts

The catalytic activity of a novel catalyst Mo/MgAl₂O₄ was studied in isobutane dehydrogenation, and the effect of calcination temperature has been comprehensively investigated. For catalysts with MoO₃ loading below monolayer coverage (5Mo/MgAl₂O₄), isobutane conversion increases with calcination temperature, while the selectivity to isobutene decreases. An opposite trend is observed for catalysts with MoO₃ loading above monolayer coverage (30Mo/MgAl₂O₄). In combination with characterization results, it can be concluded that calcination temperature affects catalyst structure and properties in many aspects including surface area, acidity and reducibility, as well as the interaction between Mo species and support, and thus influences the catalytic behaviors.     

铂锡催化剂用于混合低碳烷烃脱氢生产异丁烯

采用炼厂异丁烷塔顶轻组分作为原料,运用Pt-Sn/Al₂O₃为脱氢催化剂生产异丁烯。通过制备不同的铂锡催化剂考察影响催化剂性能的各种因素。结果表明,异丁烷的转化率随着Pt含量的增加先增大后减小,在0.40%左右达到最大值,反应8 h后仍然保持在35%以上,同时异丁烯的收率也能保持在22%以上。异丁烷的转化率和异丁烯的选择性均随Pt/Sn原子比的增大呈现先增大后减小的趋势,并且在Pt/Sn原子比为2∶3时,异丁烯的收率达到最大,反应8 h后仍能达到26%以上。通过碱溶电位滴定法分析催化剂中的氯含量,研究了氯含量与催化剂性能的关系。结果表明,随着氯含量增大,异丁烷的转化率不断上升,而异丁烯的选择性不断下降。综合考虑异丁烯的收率和转化率及选择性,催化剂中氯含量为相似文献   

异丁烷脱氢过程催化剂结焦与焦性质研究

在固定床反应装置上,采用YBD型Cr/Al_2O_3催化剂催化异丁烷脱氢,通过热分析技术研究结焦催化剂,考察反应条件对催化剂结焦量及焦性质的影响。结果表明,Cr/Al_2O_3催化剂对异丁烷脱氢有较好的催化活性,当反应温度580℃,空速800 h^(-1)时,异丁烷转化率60%以上,异丁烯选择性90%以上,异丁烯收率约60%。反应温度、空速以及异丁烯对结焦催化剂的焦含量有明显影响,当反应温度超过580℃,随着原料气中异丁烯含量的增加,催化剂的结焦量迅速增加。     

Oxidation of isobutane on a heteropolycompound hydrogen reservoir

The selective oxidation of isobutane to methacrylic acid (MAA) has been studied on Cs_1.6H_2.4P_1.7Mo₁₁V_1.1O₄₀ which is a heteropolycompound (HPC). The oxidation mechanism isobutane → isobutene → MAL → MAA has already been proposed previously with a rate determining step corresponding to the first step of the reaction, i.e., to dehydrogenation of isobutane leading to isobutene. Here we show that the HPC which is active in the oxidation of isobutane possesses, in the reduced state, anionic vacancies able to store reactive hydrogen species H ^* presenting the ability to diffuse through the solid. Such a result is of great importance since dehydrogenation requires the abstraction of hydrogen from the molecule which could be performed by a lacunar phase. Therefore, a mechanism of the dehydrogenation step is proposed, involving a heterolytic abstraction of a H⁻ species from the alkane.