不同载体对Pt-Sn催化剂丙烷催化脱氢性能影响

分别以Hβ分子筛和γ-Al₂O₃为载体,采用浸渍法制备不同Sn含量的负载型Pt-Sn双组分丙烷催化脱氢催化剂。在固定床微反装置上对制备的催化剂进行活性评价,并采用NH₃-TPD方法测定催化剂表面酸量和酸强度分布。结果表明,负载型Pt-Sn/Hβ和Pt-Sn/γ-Al₂O₃催化剂对丙烷催化脱氢反应性能与Sn含量密切相关,弱酸中心的存在对丙烷催化脱氢反应有利,对于特定的Pt-Sn体系,γ-Al₂O₃为载体的催化剂性能优于Hβ分子筛为载体的催化剂,当负载Sn质量分数为0.9时,Pt-Sn/γ-Al₂O₃催化剂性能最好。     

N掺杂石墨烯负载Pt-Sn催化剂的制备及电催化性能研究

氮掺杂石墨烯负载Pt在直接乙醇燃料电池（DEFCs）中表现出较好的性能。Pt的高成本极大地限制了DEFCs的商业化应用。因此,采用一系列不同浓度水合肼还原氧化石墨烯的简单方法,合成了氮掺杂石墨烯负载Pt-Sn （Pt-Sn/G-N）。研究了Pt-Sn/G-N催化剂纳米粒子的均匀分散对乙醇氧化的电催化活性影响。通过控制不同的氮含量,进一步研究了Pt和Sn金属颗粒最适宜协同效应的比例。结果表明：当氧化石墨烯与水合肼的质量比为1∶7时,催化剂的Pt和Sn负载均最大,Pt与Sn的比值为1.41,Pt/Sn合金的平均粒径最小（1.8 nm）。此外,与其他催化剂相比,Pt-Sn/G-N （1∶7）具有最高的电催化活性,稳定性好,抗CO中毒能力强。即Pt-Sn/G-N （1∶7）的Pt与Sn实现了催化协同作用,为Pt-Sn催化剂在直接乙醇燃料电池（DEFCs）中的应用提供了更多的途径。     

Dehydrogenation of C3–C4 paraffin's to corresponding olefins over slit-SAPO-34 supported Pt-Sn-based novel catalyst

The objective of this work is to discuss the performance of Pt-Sn/slit-SAPO-34 novel catalyst for selective C₃–C₄ dehydrogenation to corresponding light olefins. The metallic contents, acidity, active metallic sites and metallic dispersion were determined using a number of physico-chemical techniques as it gives a justification for superior catalytic activity for dehydrogenation reaction. The Pt-Sn/slit-SAPO-34 catalyst was analyzed for dehydrogenation activity under optimized operating conditions; at atmospheric pressure, hydrogen to alkane (feed) molar ratio is 0.2, weight hourly space velocity 5 h^?1 and temperature 585 °C. Around 40% light alkane conversion and above 95% of total olefins selectivity with 94% propene, 92% n-butene and about 84% iso-butene selectivity were achieved over Pt-Sn/slit-SAPO-34 novel catalyst. The catalyst was parametrically characterized over the above said operating conditions and effects of operating conditions on product distribution were discussed. The coke formation was inherently related to catalyst activity in dehydrogenation reaction and related to surface intermetallic ensemble effects; and ultimately the prominent stakeholder in catalyst deactivation. The novel catalysts also showed very good hydrothermal stability in a continuous reaction–regeneration cycles due to silica-based acidic structure of support. The results obtained over Pt-Sn/slit-SAPO-34 novel catalyst were compared with other Pt-Sn-based ZSM-5 and SAPO-34 supported catalysts of similar active metallic content under identical operating conditions.     

Mn（Salen）／Al-HMS催化剂微波固相法制备及其催化性能

采用新的微波固相法制备出Mn(Salen)/Al-HMS催化剂。通过FT IR和TG的表征,结果表明,微波固相方法成功地将Mn(Salen)配合物固载于介孔Al-HMS分子筛中。以苯乙烯环氧化反应为例比较了不同方法制备的催化剂的催化性能,发现微波固相法制备的Mn(Salen)/Al-HMS-IP催化剂具有较高的催化活性和最好的环氧化物选择性,此外,考察了催化剂性能还与制备过程中的微波辐射时间、反应时间、反应溶剂、反应温度、氧化剂的用量及催化剂的重复使用对微波固相法制备的催化剂的性能影响规律,得到了满意的结果。     

Mn(Salen)/A1-HMS催化剂微波固相法制备及其催化性能

采用新的微波固相法制备出Mn(Salen)/Al-HMS催化剂.通过FTIR和TG的表征,结果表明,微波固相方法成功地将Mn(Salen)配合物固载于介孔Al-HMS分子筛中.以苯乙烯环氧化反应为例比较了不同方法制备的催化剂的催化性能,发现微波固相法制备的Mn(Salen)/Al-HMS-IP催化剂具有较高的催化活性和最好的环氧化物选择性,此外,考察了催化剂性能还与制备过程中的微波辐射时间、反应时间、反应溶剂、反应温度、氧化剂的用量及催化剂的重复使用对微波固相法制备的催化剂的性能影响规律,得到了满意的结果.     

助催化剂Sn、Ga、In和K对丙烷脱氢催化剂Pt/Al2O3

用廉价的丙烷脱氢制丙烯是解决丙烯供应紧张问题的途径之一,研究优异性能的丙烷脱氢催化剂具有重要意义。采用分步浸渍法制备不同类型的丙烷脱氢催化剂Pt/Al₂O₃,在固定床反应器中考察助催化剂Sn、Ga、In和K对催化剂性能的影响。结果表明,Pt-Sn/Al₂O₃催化剂性能略优于Pt-Ga/Al₂O₃和Pt-In/Al₂O₃,并且比较稳定。在Pt-Sn/Al2O3催化剂中加入适量K,可有效改善催化剂性能,但高温条件下积炭严重,有待深入研究和改进。     

Catalytic dehydration of methanol to dimethyl ether (DME) over Al-HMS catalysts

A series of Al-HMS with different Si/Al ratio was used as a solid acid catalyst for methanol dehydration to dimethyl ether (DME). The effect of temperature, feed composition, space velocity, and the catalyst Si/Al ratio on the catalytic dehydration of methanol was investigated. By decreasing Si/Al, the temperature required to reach equilibrium conversion of methanol decreased due to the increased number of acidic sites. Compared to commercial γ-Al₂O₃, Al-HMS-5 and Al-HMS-10, catalysts exhibited a high yield of DME. Among all Al-HMS catalysts, Al-HMS-10 exhibited an optimum yield of 89% with 100% selectivity and excellent stability for methanol dehydration to DME.     

Novel BN supported bi-metal catalyst for oxydehydrogenation of propane

A novel boron nitride (BN) supported Pt-Sn catalyst was used for the oxydehydrogenation of propane. BN is a graphite-like inert support which provides negligible interaction with metals. The Pt-Sn/BN catalysts were prepared by co-incipient wetness impregnation with various Sn loadings. A commercial support γ-Al₂O₃ was chosen to compare with BN. PtSn alloys were formed due to the partially reduced Sn in Pt-Sn/BN catalyst in H₂ at 400 °C. Furthermore, the crystalline phases of PtSn and SnPt₃ alloys were also observed from the XRD patterns of Pt-Sn/BN catalysts. However, PtSn alloys were not detected in Pt-Sn/γ-Al₂O₃ by XRD. The Sn addition clearly improved the activity and propylene selectivity of Pt-Sn/BN at 600 °C. The more the Sn loading, the higher the selectivity and yield of propylene were. A maximum yield of propylene (38.3%) was achieved on Pt-Sn (0.75 wt%)/BN catalyst at the start of reaction. The catalysts, Pt-Sn/γ-Al₂O₃, deactivated more rapidly than Pt-Sn/BN. The activity and selectivity enhancement are attributed to the formation of PtSn and/or SnPt₃ alloy particles on the BN support. Compared with the hydrophilic γ-Al₂O₃, the hydrophobic BN surface can expel H₂O during the oxidation of hydrogen resulting in the activity increase.     

长链烷烃（n-C10~13）脱氢制单烯烃催化剂的研究Ⅱ.Pt-Sn/MgAl2O4催化剂上C12脱氢反应行为

采用真空浸渍法制备Pt-Sn/MgAl₂O₄和Pt-Sn/γ-Al₂O₃催化剂。对两种催化剂进行C₁₂脱氢催化性能评价比较,并使用BET、XRD、CO吸附、TPR、NH₃-TPD和TG等手段对催化剂进行表征。NH₃-TPD测定结果表明, Pt-Sn/MgAl₂O₄催化剂比Pt-Sn/γ-Al₂O₃催化剂具有较弱的酸性。Pt-Sn/MgAl₂O₄催化剂的初始转化率(21.6%)比Pt-Sn/γ-Al₂O₃催化剂初始转化率(22.6%)低,但其单烯烃选择性(83.9%)比后者(73.6%)高。     

Effect of Al and Ti content in HMS material on the catalytic activity of NiMo and CoMo hydrotreating catalysts in the HDS of DBT

Al- and Ti-containing HMS materials, with a Si/M (Me = Al(Ti)) molar ratio equal to 40, were used as supports for preparing NiMo and CoMo HDS catalysts. The supports and catalysts were characterized by N₂ adsorption–desorption (S_BET), X-ray diffraction (XRD), UV–vis diffuse reflectance (DRS UV–vis), temperature-programmed reduction (TPR) and Raman spectroscopy. The catalysts were tested in the hydrodesulphurization (HDS) reaction of dibenzothiophene (DBT). All supported NiMo and CoMo catalysts on Al-HMS and Ti-HMS substrates showed higher catalytic activity than their Me-free counterparts. We found two interesting correlations between the structure and chemical coordination of the supported oxide precursors and catalytic activity. The differences observed in catalyst performance are attributed to the structure and specific electronic properties of the supported active species. From our results, it appears possible to optimize the Al- and Ti-loading to maximize the HDS activity.     

系列Pt-X合金型PEMFC阳极催化剂的制备及表征

引言质子交换膜燃料电池(PEMFC)除具有燃料电池的一般特点之外,还具有可在室温下快速启动、无电解质流失、寿命长、比功率与比能量高等突出优点,因而成为当今最具发展前景的一类燃料电池。由于工作温度低于100℃,主要采用过电势较低且活性较高的Pt为电催化剂,因此它存在价     

SiW/Al-HMS上的甲苯与叔丁醇的烷基化反应

以十二烷基胺为模板剂合成中孔分子筛Al-HMS,并将硅钨杂多酸(SiW12)浸渍固载在Al-HMS上,用XRD、FT-IR和NH3-TPD对Al-HMS以及不同负载量的催化剂进行了表征。结果发现,当SiW负载量为40%时,SiW仍然均匀分布在载体表面上。考察了Al-HMS负载SiW用于甲苯与叔丁醇的烷基化反应的催化性能。当负载量为40%时,催化剂的酸量最大、活性最好。采用40%SiW/Al-HMS为催化剂,研究了各种反应条件对催化剂性能的影响。实验结果表明,在适宜的操作条件下即反应温度453 K、反应时间4 h、叔丁醇与甲苯的摩尔比为3、原料与催化剂的质量比为3、初始压力0.60 MPa的条件下,甲苯转化率为56.77%,对叔丁基甲苯的选择性为73.15%。     

丁烷中硫化物对Pt-Sn催化剂脱氢性能的影响

以三种不同硫含量的混合丁烷为原料,在相同工艺条件下,对丁烷脱氢Pt-Sn催化剂的催化性能进行了比较,结果表明:原料中的硫含量是影响催化剂催化性能及寿命的一个重要因素,硫含量越高,其寿命越短,选择性和转化率下降速率越快。烧焦再生后的催化剂活性无法恢复。     

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。     

Characterization and activity of Pt-Sn/Al2O3 catalysts of different preparation: coimpregnation and new Pt-Sn precursor

A new bimetallic Pt-Sn compound [Pt(NH₃)₄][SnCl₆] has been used as precursor for the preparation of supported Pt-Sn/Al₂O₃ catalysts. A comparison of a dried sample with that prepared by coimpregnation displays different behaviour in TPR, chemisorption. The initial catalytic activity properties were checked in the reactions of cyclohexane dehydrogenation and cyclopentane ring opening, whilen-hexane skeletal reactions were used to probe the quasisteady-state activity. The catalyst prepared via the Pt-Sn complex precursors exhibited some-what lower specific activity. This fact, together with enhanced olefin formation fromn-hexane was taken as an indication of lower amount of contiguous Pt atoms and some electronic interaction between Pt and Sn in that catalyst.On leave from Fachhochschule Ostfriesland, D-26723 Emden, Germany.     

Decane reforming reaction over Pt,Ir, Pt-Ir and Pt-Ni bimetallic catalysts supported on Y-zeolite

Pt, Ir, Pt-Ir and Pt-Ni bimetallic catalysts supported on NaY- and HY-zeolite were examined as a catalyst for producing gasoline from n-decane via simultaneous reforming and cracking. The catalysts were prepared by calcining and reducing metal-ion-exchanged Y-zeolite with O₂ and H₂ at 300°C., respectively. Thus prepared catalysts were characterized by hydrogen chemisorption and temperature programmed desorption of ammonia. Pt-Ni/NaY and Pt-Ir/NaY bimetallic catalysts offered the improved activity maintenance compared to Pt/NaY monometallic catalyst. The catalysts supported on HY-zeolite showed higher selectivity toward C₅–C₇ and skeletal isomers of C₅–C₇- and C₈–C₁₀ than those of the catalysts supported on NaY-zeolite, which is a desired characteristic for increasing octane value of gasoline these days. However, deactivation with reaction time was much more pronounced on HY-zeolite-supported catalyst. When the catalyst was prcsulfided with H,S, the stability with time on stream was enhanced and the selectivity was quite different from that of the catalyst before presulfiding. The acidity of Y-zeolite and presulfiding of catalyst greatly influenced the activny, selectivity and stability of Pt, Ir, Pt-Ir and Pt-Ni bimetallic catalysts supported on Y-zeolite in n-decane reforming reaction.     

A molecular kinetic model incorporating catalyst acidity for hydrocarbon catalytic cracking

This work built a molecular-level kinetic model for hydrocarbon catalytic cracking, incorporating the catalyst acidity as the parameter to estimate reaction rates. The n-decane and 1-hexene co-conversion catalytic cracking process was chosen as the studying case. The molecular reaction network was automatically generated using a computer-aided algorithm. A modified linear free energy relationship was proposed to estimate the activation energy in a complex reaction system. The kinetic parameters were initially regressed from the experimental data under several reaction conditions. On this basis, the product composition was evaluated for three catalytic cracking catalysts with different Si/Al. The Bronsted acid and Lewis acid as the key catalyst properties were correlated with kinetic parameters. The built model can calculate the product distribution, gasoline composition, and molecular distribution at different reaction conditions for different catalysts. This sensitive study shows that it will facilitate the model-based optimization of catalysts and reaction conditions according to product demands.     

浸渍法制备Pt-Sn/γ-Al2O3催化剂及其催化性能

采用等体积共浸渍法和分步浸渍法制备Pt-Sn/γ-Al₂O₃催化剂,并在固定床反应器上进行正丁烷脱氢实验研究。结果表明,与共浸渍法相比,分步浸渍法制备的催化剂表现出更高的催化活性。采用等体积浸渍法制备催化剂时,活性组分与载体之间会发生竞争吸附作用,这会影响活性金属组分在载体表面的分散度,进而影响催化剂活性。     

The electro-oxidation of carbon monoxide, hydrogen/carbon monoxide and methanol in acid medium on Pt-Sn catalysts for low-temperature fuel cells: A comparative review of the effect of Pt-Sn structural characteristics

The electrocatalytic activity for CO, H₂/CO and CH₃OH oxidation of Pt-Sn catalysts has been extensively investigated for a possible use as anode materials for low-temperature fuel cells. This paper presents an overview of the relationship between the structural characteristics of the catalysts (catalyst composition, degree of alloying, presence of oxides) and their electrocatalytic activity for the oxidation of the different fuels.     

低碳烷烃脱氢催化剂的研究进展

叙述了低碳烷烃脱氢研究的发展现状。介绍了低碳烷烃脱氢的方法,包括无氧脱氢法和有氧脱氢法。用于低碳烷烃脱氢的Pt基催化剂主要缺点是稳定性差、选择性低。分别介绍了Pt基催化剂的活性组分、载体及不同助剂添加对Pt-Sn催化剂性能的影响。简单介绍了铬系催化剂以及国外低碳烷烃脱氢的技术工艺。最后对低碳烷烃脱氢催化剂的发展趋势做了展望。