碘催化氧化甲烷制甲醇催化剂

碘催化氧化甲烷制甲醇催化剂美国南加利福尼亚州大学洛克尔烃研究所研究人员发现 ,碘溶解在发烟硫酸中形成的溶液是甲烷低温氧化的有效催化剂。碘发烟硫酸溶液催化甲烷转化形成硫酸氢甲酯 ,后者再与水反应很容易生成甲醇。据称 ,这是迄今报道的在 2 0 0℃以下将甲烷转化成一种甲基产物的最简单的催化体系。其甲烷转化率在 40 %以上 ,硫酸氢甲酯选择性在 95 %以上 ,在已报道的数据中属最高的一类。而且 ,这种氧化体系与其他甲烷氧化体系不同 ,不需要过氧化氢等昂贵的催化剂碘催化氧化甲烷制甲醇催化剂     

甲烷低温活化制甲醇研究进展

简要评述了当前国内外在甲烷直接部分氧化合成甲醇和甲烷经卤代后合成甲醇领域的研究进展。众多研究表明,甲烷多相催化氧化制甲醇是最具有工业化应用前景的技术,其中钼系催化剂的效果较好;以Pt、Pd配合物为催化剂的甲烷液相催化氧化法制甲醇方法具有较高的甲烷转化率和甲醇选择性,但是催化剂价格昂贵、反应条件苛刻、环境污染严重;甲烷气相均相氧化属于非催化反应,在高温高压下进行,且反应器须具备特殊的形式,结构复杂;虽然酶催化氧化法的选择性较高,但是生物酶的制备有一定难度,不适用于大范围应用,该路线目前仅限于实验室研究阶段;光催化氧化是一种环境友好的技术,反应条件温和、避免氧化剂应用,但是该类催化剂局限于半导体和盐类,还有待于进一步开发新型高效的催化剂。同时,甲烷经卤代后合成甲醇的方法对解决甲烷活化的难题具有独特优势,是一种比较有开发前景的路线,正在受到研究者们的密切关注。     

V2O5催化甲烷液相部分氧化工艺过程研究

以V2O5为催化剂,在发烟硫酸中进行了甲烷液相选择性氧化的研究工作,考察了V2O5催化剂用量、反应温度、反应时间、发烟硫酸浓度等工艺条件对反应收率的影响,进行了甲烷液相选择性氧化的催化机理探讨和宏观动力学推导.甲烷在部分氧化反应中首先转化为硫酸甲酯,后者进一步水解得到甲醇.甲烷转化率可达54.5%,选择性45.5%,相应的工艺条件为催化剂用量0.0175 mol、反应温度180C、发烟硫酸中SO3含量50%(wt)、反应时间2 h.V2O5催化甲烷液相部分氧化反应遵循亲代取代机理,甲烷液相部分氧化反应为一级反应.     

碘催化氧化甲烷制甲醇催化剂

本刊讯　据报道 ,美国南加利福尼亚州大学洛克尔烃研究所研究人员发现 ,碘溶解在发烟硫酸中形成的溶液是甲烷低温氧化的有效催化剂。碘发烟硫酸溶液有稳定的活性 ,催化甲烷转化形成硫酸氢甲酯 ,后者再与水反应很容易生成甲醇。就其所知 ,这是迄今报道的在 2 0 0℃以下将甲烷转化成一种甲基产物的最简单的催化体系。其甲烷转化率在 4 0 %以上 ,硫酸氢甲酯选择性在 95 %以上 ,在已报道的数据中居最高。而且 ,这种氧化体系与其他甲烷氧化体系不同 ,不需要过氧化氢等昂贵的催化剂碘催化氧化甲烷制甲醇催化剂$《化学工程新闻》!美国…     

碘催化氧化甲烷制甲醇催化剂问世

据美国《化学工程新闻》报道 ,美国南加利福尼亚州大学洛克尔烃研究所研究人员发现 ,碘溶解在发烟硫酸中形成的溶液是甲烷低温氧化的有效催化剂 .研究人员说 ,碘发烟硫酸溶液有稳定的活性催化甲烷转化形成硫酸氢甲酯 ,后者再与水反应很容易生成甲醇 .他们说 ,就其所知 ,这是迄今报道的在 2 0 0℃以下将甲烷转化成一种甲基产物的最简单的催化体系 ,其甲烷转化率在 4 0 %以上 ,硫酸氢甲酯选择性在 95 %以上 ,在已报道的数据中属最高的一类 ,而且这种氧化体系与其他甲烷氧化体系不同 ,不需要过氧化氢等昂贵的催化剂碘催化氧化甲烷制甲醇催化剂…     

CoMoO4负载Mo-V-Cr-Bi氧化物催化剂上甲烷部分氧化的研究

研究了CoMoO4负载Mo-V-Cr-Bi氧化物催化剂上甲烷部分氧化反应,发现反应存在一转折温度,当反应温度低于此温度时,CO是主要产物,而部分氧化产物甲醇的选择性低于20%,而当反应温度高于此温度时,CO的选择性大大降低,而CO2的选择性大大升高,主要产物变为CO2,甲醇的选择性降为0。在O2完全反应的时候,总会有H2生成,特别当反应温度高于转折温度的时候,H2的生成量大大增加。     

CH_4/O_2等离子体反应直接合成甲醇的研究

高效甲烷转化技术一直是学术界及工业界的研究热点,其中,甲烷转化制甲醇颇受业界关注。然而,甲烷分子结构稳定且C—H键能大(413 k J/mol)导致转化困难。采用新型介质阻挡放电反应器,以循环水为接地极,在低温常压条件下通过分子氧实现甲烷直接氧化制甲醇。结果表明,在短停留时间和低功率条件下可以达到较高的甲醇选择性,在温度为85℃、n(CH4)∶n(O2)为2∶1、停留时间为0. 393 s和功率为30 W条件下,甲烷转化率达到4. 1%,甲醇选择性达到42. 2%,液体产物选择性达到76. 2%。     

霍尼韦尔完成对ASPEN科技公司的收购

美国商务部新技术开发计划(ATP)机构为UOP公司的选择性液相氧化甲烷制甲醇新技术颁发了奖励基金。预计开发工作为期3年，共需资金500万美元，ATP将负责提供200多万美元的资金。     

甲烷液相部分氧化合成甲醇过程研究

以碘系列化合物为催化剂,在发烟硫酸溶剂中进行了甲烷液相选择性氧化制取甲醇。考察了催化剂种类、用量、反应温度、发烟硫酸浓度等工艺条件对反应收率的影响,探讨了甲烷液相选择性氧化的催化机理以及发烟硫酸中 SO3 含量的作用。实验结果表明,甲烷液相部分氧化的最佳催化剂为 I2,最佳的工艺条件为催化剂浓度为0.099 mol?L?1、反应温度 473K、发烟硫酸(SO350%(wt))、反应时间 3h。 在此条件下,甲烷转化的转化率可达 82.65%,选择性可达 70.43%。机理研究表明,甲烷在部分氧化反应中首先转化为硫酸单甲酯,然后进一步水解得到甲醇, 反应遵循亲电取代机理。发烟硫酸中的游离 SO3的作用就在于提供较好的亲电环境、反应的氧源以及亲核试剂。     

新颖的甲烷选择性氧化制甲醇固体催化剂

本刊讯 德国《应用化学》期刊最近发表了新型Pt基固体催化剂用于甲烷选择性氧化制甲醇的研究成果。该催化剂在低温下具有高活性，并可反复使用。这一最新研究进展有可能加速甲烷制高附加值及易于运输的液体产品技术的商业化进程。     

Continuous methanol synthesis directly from methane and steam over Cu(II)-exchanged mordenite

The formation of methanol directly from methane and steam was observed over Cu ion-exchanged mordenite. Furthermore, the continuous production of methanol was achieved by co-feeding methane and steam over Cumordenite. The methanol production rate was comparable to that reported in the stepwise process in which activation, methane reaction, and extraction of methanol were carried out separately.     

膜催化技术用于甲烷转化反应的研究进展

介绍了膜催化技术在甲烷转化反应中的应用,这些过程包括甲烷氧化偶联反应制乙烯,甲烷部分氧化制甲醇,甲烷水蒸气重整制合成气等,通过膜催化反应与传统催化反应的比较,揭示了膜催化技术的优点。     

Structural and mechanistic insights into methane oxidation by particulate methane monooxygenase

Particulate methane monooxygense (pMMO) is an integral membrane copper-containing enzyme that converts methane to methanol. Knowledge of how pMMO selectively oxidizes methane under ambient conditions could impact the development of new catalysts. The crystal structure of Methylococcus capsulatus (Bath) pMMO reveals the composition and location of three metal centers. Spectroscopic data provide insight into the coordination environments and oxidation states of these metal centers. These results, combined with computational studies and comparisons to relevant systems, are discussed in the context of identifying the most likely site for O 2 activation.     

天然气制甲醇合成气工艺及进展

论述了国内外天然气制甲醇合成气各工艺的研究现状,进展及发展方向。天然气制合成气的典型工艺是水蒸气催化转化法,其技术成熟,但投资大,能耗高,生产的合成气不适于直接用来合成甲醇。天然气与CO2催化转化工艺可制得富含CO的合成气,解决蒸气转化法氢过剩的问题,实现CO2的减排,目前对该法的研究主要集中在开发新型催化剂和优化反应条件等。两段转化法即一段炉采用蒸气转化,两段炉用富氧或纯氧转化,无需经转化炉前或炉后添加二氧化碳,就可达到合成甲醇原料气成分的要求。甲烷部分氧化法能耗低,反应易控制,可制得符合比例要求的甲醇合成气,但尚未见到该技术工业化的相关报道。甲烷自热转化工艺是在反应器中耦合了放热的甲烷部分氧化反应和强吸热的甲烷蒸气转化反应,反应体系本身可实现自供热,该工艺一般采用富氧空气或氧气,因此需氧气分离装置,增加了投资,这是制约其发展和应用的主要障碍。     

Partial oxidation of methane using a microscale non-equilibrium plasma reactor

A flow-type, microscale, non-equilibrium plasma reactor was developed for partial oxidation of methane without a catalyst. A wide range of oxygen and methane mixtures was directly processed without dilution or explosion at ambient temperature because the microscale plasma reactor removes excess heat generated by partial oxidation, thereby maintaining a reaction field at temperatures near room temperature. Consequently, the least reactive methane was excited by high-energy electrons, whereas successive destruction of reactive oxygenates was minimized simultaneously within the extremely confined environment. A highly reactive and quenching environment is thereby obtained within a single reactor: these are paradoxical conditions in conventional thermochemical processes. A major product among liquid oxygenates was methanol, whose selectivity reached 34% at 30% of methane conversion. Selectivity of oxygenates such as methanol and formaldehyde depends strongly on the fragmentation pattern of methane dissociation by electron impact. Maximum selectivity of oxygenates, which is estimated from numerical simulation of a filamentary microdischarge, reaches 60% when the applied electric field corresponds to the breakdown field of methane (80 Td, 1 Td = 10⁻¹⁷ V cm²). The discharge current increases markedly with an applied electric field, but the selectivity of oxygenates decreases as the field strength increases.     

甲烷直接氧化制甲醇研究新进展

文章主要介绍了国内外在甲烷直接氧化制甲醇研究方面取得的最新进展。其中包括传统催化氧化,酶催化氧化,光催化氧化,非热式等离子体在合成甲醇中的应用和膜技术的应用。     

Modified Sulfonated Poly(ether ether ketone) Based Mixed Matrix Membranes for Direct Methanol Fuel Cells

Mixed matrix membranes based on zeolite 4A‐methane sulfonic acid (MSA)‐sulfonated poly(ether ether ketone) (SPEEK) are evaluated as a potential polymer electrolyte membrane (PEM) for direct methanol fuel cells (DMFCs). Ion‐exchange capacity, sorption of water, and water–methanol mixture, proton conductivity, and methanol permeability for the mixed‐matrix membranes have been extensively investigated. The mixed‐matrix membranes are also characterized for their cross‐sectional morphology, mechanical, and thermal properties. DMFCs employing SPEEK‐MSA (20 wt.%) blend, zeolite 4A (4 wt.%)‐SPEEK‐MSA (20 wt.%) mixed matrix membranes deliver peak power densities of 130 and 159 mW cm^–2, respectively; while a peak power density of only 95 mW cm^–2 is obtained for the DMFC employing pristine SPEEK membrane at 70 °C. The results showed that these SPEEK based mixed matrix membranes exhibit higher DMFC performance and lower methanol permeability in comparison to Nafion‐117 membrane.     

An efficient technique for improving methanol yield using dual CO2 feeds and dry methane reforming

Steam methane reforming (SMR)-based methanol synthesis plants utilizing a single CO₂ feed represent one of the predominant technologies for improving methanol yield and CO₂ utilization. However, SMR alone cannot achieve full CO₂ utilization, and a high water content accumulates if CO₂ is only fed into the methanol reactor. In this study, a process integrating SMR with dry methane reforming to improve the conversion of both methane and CO₂ is proposed. We also propose an innovative methanol production approach in which captured CO₂ is introduced into both the SMR process and the recycle gas of the methanol synthesis loop. This dual CO₂ feed approach aims to optimize the stoichiometric ratio of the reactants. Comparative evaluations are carried out from a techno-economic point of view, and the proposed process is demonstrated to be more efficient in terms of both methanol productivity and CO₂ utilization than the existing stand-alone natural gas-based methanol process.     

Influence of forced feed composition cycling on catalytic methanol synthesis

Studies have been carried out between 230 and 270°C and 1.97 and 2.93 MPa total pressure on the synthesis of methanol over an industrial catalyst of the copper-zinc oxide-alumina type using a gradientless reactor. Two modes of forced feed composition cycling were explored: periodic variations of the mole fraction of H₂ and CO and periodic variation of the CO₂ content. The latter mode substantially improved methanol production and suppressed the parasitic formation of methane, while the former mode had just the opposite effect. Measurements of methanol, methane and CO during a cycle as well as separate observations of the response to step-changes in concentration indicated substantial storage of CO on the catalyst surface. Rapid response of methane to the CO₂ content suggests over-reduced areas of the catalyst surface are responsible for methane formation and that these regions are readily oxidized. CO₂ or H₂O associated with methane formation appear to relate to the dynamics of methanol formation.     

Methanol formation from methane partial oxidation in CH4–O2–NO gaseous phase at atmospheric pressure

The reaction condition for high yield of methanol in a gaseous reaction between methane and oxygen in the presence of NO at atmospheric pressure was explored. Methane partial oxidation without NO (CH₄–O₂) gave only 1% conversion of methane at 966 K. The addition of NO led to a remarkable increase in methane conversion and to high selectivity to C₁-oxygenates. The conversion of methane attained 10% at 808 K in the presence of NO (0.5%) where the selectivities to methanol and formaldehyde were 22.1 and 24.1%, respectively. Nitromethane and carbon oxides were also observed in the product gas. The amount of nitromethane was almost equal and/or near to that of initial NO. The carbon monoxide produced was several times higher than carbon dioxide. Influences of NO concentration, ratio of methane to oxygen, water vapor, and dilution with helium gas on product distribution were measured. Low concentration of NO (0.35–0.55%) was favorable for methanol formation. High selectivity to methanol was obtained at low value of the ratio of methane to oxygen (2.0–3.0) or low concentration of dilution gas (<16%). The NO₂ added promoted methane partial oxidation and selectivity to methanol. Therefore, it was assured that NO_x promoted the formation of CH₃√ and CH₃O√ in the gas phase reaction for CH₄–O₂–NO.