Site Selective Detection of Methane Dissociation on Stepped Pt Surfaces

Topics in Catalysis - We report a combined experimental and theoretical study comparing methane dissociation on three different platinum surfaces Pt(111), Pt(211), and...     

Determination of Surface Areas of Active Carbons by Retention of Ethylene Glycol and Ethylene Glycol Monoethyl Ether

Abstract

Experiments of ethylene glycol and ethylene glycol monoethyl ether retention on some active carbons were carried out to measure the surface areas of the carbons. Some differences were observed between nitrogen-specific surface area values and those obtained from ethylene glycol retention. However, since the differences decreased through an increase of surface oxygen content as a result of treatment of the carbons with H₂O₂, it was evident that ethylene glycol retention depended upon the surface oxygen content. Also, the surface area values obtained from retention of ethylene glycol monoethyl ether did not depend upon the surface oxygen content. Measurements of the ethylene glycol monoethyl ether retention process could be performed in a shorter time than the equivalent ethylene glycol retention measurements.     

乙烯-1,3,5-三甲苯的气液相平衡与乙烯回收工艺的流程模拟(英文)

The amount of ethylene in refinery off-gas is high with a mass fraction of 20%,but the refinery off-gas is usually used as fuel gas in most refineries.The separation and recovery of ethylene is of remarkable significance for saving energy and reducing carbon dioxide emission.The aim of this paper is to use a novel absorbent mesitylene for the ethylene absorption process and assess its application feasibility through the ethylene + mesitylene vapor-liquid equilibrium data measurement and its binary interaction parameter correlation,as well as the simulation for ethylene separation process.     

环氧乙烷装置排放气中乙烯的回收

讨论了环氧乙烷装置排放气的组成及其对氧化反应的影响，提出了对乙烯进行回收的工艺技术要求，分析比较了国内外不同回收工艺包括变压吸附、膜分离、吸附分离等技术的发展概况，提出变压吸附技术由于工艺简单，适应性强，是一种较有发展前景的回收工艺。     

一种用于乙二醇残液回收的浸没蒸发器

利用浸没蒸发原理发明了一套用于乙二醇残液回收的浸没蒸发设备,同时改变浸没蒸发动力来源,降低能耗水平,对锅炉尾气资源加以充分利用,为浸没蒸发设备在资源化利用领域的使用提供一种可能.     

提高脱甲烷系统乙烯回收率方法的比较

分析了不同专利的尾气精馏塔系统的设置情况.在相同基准上就四个方案进行模拟计算,围绕乙烯回收率、能耗和固定投资三个方面进行比较.比较结果表明,专利CN 1048713C的甲烷吸收塔流程是最经济的提高脱甲烷系统乙烯收率的方案.     

Oxygen Reduction Reaction on Pt and Pt Bimetallic Surfaces: A Selective Review

In this review we selectively summarize recent progress, primarily from our laboratory, in the development of the oxygen reduction reaction (ORR) catalysis on well‐defined surfaces. The focus is on two type of metallic surfaces: platinum single crystals and bimetallic surfaces based on platinum. The single crystal results provide insight into the effects of the platinum structure on the kinetics of the ORR, and create a fundamental link between the specific activity of Pt (rate per unit area) and particle size (for various particle shapes). The results show that the structure sensitive kinetics of the ORR arise primarily due to structure sensitive adsorption of anions. In the absence of specific adsorption, such as in Nafion polymer electrolyte, no particle size effect is expected. The knowledge of the electrocatalysis of the ORR on model bimetallic surfaces on Pt‐Ni and Pt‐Co bulk alloys was used to resolve the enhanced ORR kinetics on supported Pt‐Ni and Pt‐Co catalysts. Finally, we show that the ORR on platinum modified with pseudomorphic Pd metal film in alkaline solution is the best catalysts ever used in O₂ reduction. For both bimetallic systems, we demonstrated that the ability to make a controlled and well characterized arrangement of two elements in the electrode surface region presage a new era of advances in the ORR electrocatalysis.     

测定fCaO后乙二醇回收装置的简易设计

笔者在回收无水乙醇装置的基础上,对测定水泥熟料fCaO后乙二醇的回收设计了一套简易装置效果很好。1 待回收乙二醇溶液的处理     

乙烯装置凝液回收系统改造

简述了中国石油新疆独山子石化公司乙烯厂乙烯装置凝液回收系统原先的流程及存在的问题,介绍了2003年6月改造后的流程及取得的经济效益。     

乙烯-醋酸乙烯共聚物中乙烯含量测定方法研究

主要研究了乙烯-醋酸乙烯共聚物(EVA)中乙烯含量的测定方法。对样品制备、溶剂选择、体系中含水量、皂化温度、皂化时间等影响测定的主要因素进行了探讨,找到了合适的测定条件。通过与真实值进行比较,皂化法的相对误差小于0.1%。能满足EVA研究中对乙烯含量的测定要求。     

Ethylene adsorption on Pt/Au/SiO2 catalysts

Ethylene adsorption on a Pt/Au/SiO₂ catalyst (2 wt% Pt; Au/Pt atomic ratio of 10) was studied using adsorption microcalorimetry and FTIR spectroscopy. Ethylene adsorption at 300 K on Pt/Au/SiO₂ produced π‐bonded, di‐σ‐bonded, and ethylidyne species with an initial heat of 140 kJ/mol, compared to a heat of 157 kJ/mol for Pt/SiO₂ on which only ethylidyne species formed. At 203 and 263 K, ethylene adsorbed on Pt as well as on Au surface atoms for the Pt/Au/SiO₂ catalyst. Quantum chemical, DFT calculations indicate that Au exerts a significantly smaller electronic effect on Pt than does addition of Sn to Pt. This revised version was published online in July 2006 with corrections to the Cover Date.     

有机蒸汽分离膜在乙烯回收中的应用

介绍了有机蒸汽分离膜的分离原理,并介绍了利用膜法乙烯回收技术应用于环氧乙烷/乙二醇装置循环排放气中回收乙烯的效果。使用该技术后,降低了乙烯及甲烷的消耗,乙烯回收率达90%以上。     

CO Poisoning of Ethylene Hydrogenation over Pt Catalysts: A Comparison of Pt(111) Single Crystal and Pt Nanoparticle Activities

The ethylene hydrogenation reaction was studied on two platinum model catalyst systems in the presence of carbon monoxide to examine poisoning effects. The catalysts were a Pt(111) single crystal and lithographically fabricated platinum nanoparticles deposited on alumina. Gas chromatographic results for Pt(111) show that CO adsorption reduces the turnover rate from 10¹ to 10^-2 molecules/Pt site/s at 413 K, and the activation energy for hydrogenation on the poisoned surface becomes 20.2 ± 0.1 kcal/mol. The activation energy for ethylene hydrogenation over Pt(111) in the absence of CO is 10.8 kcal/mol. The Pt nanoparticle system shows the same rate for the reaction as over Pt(111) in the absence of CO. When CO is adsorbed on the Pt nanoparticle array, the rate of the reaction is reduced from 10² to 10⁰ nmol/s at 413 K. However, the activation energy remains largely unchanged. The Pt nanoparticles show an apparent activation energy for ethylene hydrogenation of 10.2 ± 0.2 kcal/mol in the absence of CO and 11.4 ± 0.6 kcal/mol on the CO-poisoned nanoparticle array. This is the first observation of a significant difference in catalytic behavior between Pt(111) and the Pt nanoparticle arrays. It is proposed that the active sites at the oxide--metal interface are responsible for the difference in activation energies for the hydrogenation reaction over the two model platinum catalysts.     

云南松松塔抗肿瘤活性部位的多糖含量测定

以葡萄糖为对照品,采用苯酚-硫酸法测定云南松松塔抗肿瘤活性部位的多糖含量。首先考察各显色条件对云南松松塔抗肿瘤活性部位多糖含量测定的影响,确定最佳显色条件为:5%苯酚用量为0.6 mL,水浴温度为60℃,水浴加热时间为20 min,浓硫酸用量为6.0 mL。该方法操作简便、稳定性好,可用于云南松松塔抗肿瘤活性部位多糖含量的测定。     

高效液相色谱法测定联苯菊酯有效成分的含量

建立了一种高效液相色谱法测定联苯菊酯有效成分含量的新方法。采用250mm×4.0 mmLichosorb Si60-5μ色谱柱,以二氯甲烷-正庚烷(V/V,80∶20)为流动相,流速为1.0mL/min,254nm紫外检测器。该方法处理简单、快速、准确、适用,方法线性范围为0.05～1.2mg/mL,天王星2.5%乳油和天王星10%乳油回收率分别为99.15%～100.82%和99.25%～100.64%,变异系数为1.18%和0.23%。     

催化裂化干气乙烯低聚催化剂活性组分研究

乙烯低聚制低碳烃是利用催化干气乙烯资源的有效途径。本文以催化干气为原料,在固定床反应装置上,采用HZSM-5催化剂,对乙烯低聚催化剂活性组分进行了研究。结果表明,活性组分含量20%~30%对提高烯烃收率有利;调节离子交换温度可以改善烯烃收率,但采用较快再生的流化床反应器更为合适。     

对氯乙烯单体精馏尾气中的乙炔进行回收利用

本文探讨了氯乙烯单体生产过程中对精馏尾气中乙炔的回收工艺方法，以提高乙炔的总转化率。     

乙二醇稳定的Pt/C催化剂的制备与表征

以乙二醇(EG)兼作溶剂和稳定剂,分别通过NaBH4和EG还原法制备了高度细化与分散的Pt/C催化剂,对其形貌、组成、结构和电化学活性比表面等进行了表征比较,并测试了它们对甲醇与乙醇电催化氧化的活性. 结果表明,2种催化剂中,Pt均为面心立方结构,粒径小且分布窄,在炭黑载体上分散均匀,单位质量Pt对甲醇与乙醇电催化氧化的活性相当;NaBH4还原法所制Pt/C催化剂中Pt0和Pt(220)晶面含量更高,Pt对甲醇与乙醇电催化氧化的峰电流密度分别为0.68与0.67 mA/cm2,分别是EG还原法所制Pt/C催化剂的1.2倍;2种催化剂对甲醇与乙醇电催化氧化的活性均与商品E-TEK催化剂相当.     

气相色谱法测定乙二醇的含量

采用气相色谱法(GC)测定乙二醇含量,色谱柱为3%FFAP不锈钢填充柱,载气为氮气,氢火焰离子化检测器。结果表明乙二醇含量在0.003～1.11kg/L范围内与峰面积呈良好的线性关系,平均回收率为99.53%。方法简便、准确、重复性好,可用于乙二醇含量的测定控制。     

Spill-Over Effects on Bimetallic Pt/Ru(0001) Surfaces

The concept of spill-over of adsorbed species has a long tradition in Heterogeneous Catalysis and has been explored also for adsorption on bimetallic surfaces, in particular by the Goodman group. In the present paper, we report results of a comprehensive temperature programmed desorption (TPD) and infrared reflection absorption spectroscopy study on spill-over effects in the adsorption and desorption of CO on structurally well defined bimetallic Pt/Ru(0001) surfaces, where part of the substrate is covered by monolayer Pt islands. While upon adsorption at 90 K, the mobility of CO_ad molecules on the surface is very limited, it is activated when the adlayer is annealed to 150 K or, more directly, if CO exposure is done at 150 K or higher temperatures. This enables diffusion of CO_ad molecules to the Pt free Ru(0001) areas, even at local CO_ad coverages which preclude further adsorption from the gas phase on the Ru parts of the surface. Spill-over processes are shown to have significant impact on the TPD spectra; furthermore they provide an additional adsorption channel for adsorption on the bare Ru(0001) areas, allowing uptake of CO at local coverages where adsorption from the gas phase is precluded. This indicates that the apparent CO saturation coverage of 0.68 ML determined for direct adsorption on Ru(0001) under UHV conditions is limited by kinetics rather than thermodynamics. The data are discussed in comparison with results and interpretations in earlier studies, which indicate that these effects are not limited to the Pt/Ru(0001) surface, but may be found on a wide range of bimetallic systems.