An IR study of methanol steam reforming over ex-hydrotalcite Cu–Zn–Al catalysts

CuO-Fe2O3 Nanoparticles Supported on SiO2 and Al2O3 for Selective Hydrogenation of 2-Methyl-3-Butyn-2-ol

In this study, novel SiO2- and Al2O3-supported Cu-Fe catalysts are developed for selective hydrogenation of 2-methyl-3-butyne-2-ol to 2-methyl-3-butene-2-ol under mild reaction conditions. TEM, XRD, and FTIR studies of adsorbed CO and TPR-H2 are performed to characterize the morphology, nanoparticle size, and particle distribution, as well as electronic state of deposited metals in the prepared catalysts. The deposition of Fe and Cu metal particles on the aluminum oxide carrier results in the formation of a mixed oxide phase with a strong interaction between the Fe and Cu precursors during the calcination. The highly dispersed nanoparticles of Fe2O3 and partially reduced CuOx, with an average size of 3.5 nm and with strong contact interactions between the metals in 5Cu-5Fe/Al2O3 catalysts, provide a high selectivity of 93% toward 2-methyl-3-butene-2-ol at complete conversion of the unsaturated alcohol.

Catalysts for Hydrogen Generation via Oxy-Steam Reforming of Methanol Process

The production of pure hydrogen is one of the most important problems of the modern chemical industry. While high volume production of hydrogen is well under control, finding a cheap method of hydrogen production for small, mobile, or his receivers, such as fuel cells or hybrid cars, is still a problem. Potentially, a promising method for the generation of hydrogen can be oxy-steam-reforming of methanol process. It is a process that takes place at relatively low temperature and atmospheric pressure, which makes it possible to generate hydrogen directly where it is needed. It is a process that takes place at relatively low temperature and atmospheric pressure, which makes it possible to generate hydrogen directly where it is needed. This paper summarizes the current state of knowledge on the catalysts used for the production of hydrogen in the process of the oxy-steam-reforming of methanol (OSRM). The development of innovative energy generation technologies has intensified research related to the design of new catalysts that can be used in methanol-reforming reactions. This review shows the different pathways of the methanol-reforming reaction. The paper presents a comparison of commonly used copper-based catalysts with other catalytic systems for the production of H₂ via OSRM reaction. The surface mechanism of the oxy-steam-reforming of methanol and the kinetic model of the OSRM process are discussed.

Oxy-Steam Reforming of Natural Gas on Ni Catalysts—A Minireview

Nowadays, the reforming of natural gas is the most common of hydrogen or syngas generation process. Each reforming process leads to the achievement of specific goals and benefits related to investment costs. The disadvantage of the reforming process is the need to preclean it mostly from the sulfur and nitrogen compounds. The solution to this problem may be liquefied natural gas (LNG). Liquefied natural gas has recently been seen as an energy source and may be a promising replacement for natural gas. The constant development of the pipeline network, safe transport and a lot of advantages of LNG were contributed to the research development related to the usage of LNG in energy generation technologies. The presented review is a literature discussion on the processing of methane used to produce hydrogen with particular emphasis on the processes of oxy-steam reforming of natural or liquefied natural gas (OSR-LNG). In addition, a key consideration in this article includes Ni catalyst systems used in the oxy-steam reforming of methane or LNG reactions. An analysis of the OSR process conditions, the type of catalyst and the OSR of the methane reaction mechanism may contribute to the development of a modern, cheap catalyst system, which is characterized by high activity and stability in the oxy-steam reforming of natural gas or LNG (OSR-LNG).

Prediction of metallic nanotube reactivity for H2O activation

The reactivity of metallic nanotubes toward the catalysis of water dissociation, a key step in the water gas shift reaction (WGSR), was analyzed through density functional theory (DFT) calculations. Water dissociation was studied on surfaces of nanotubes based on copper, gold and platinum, and also on platinum doped copper and gold nanotubes. Gold and copper nanotubes present activities that are similar to those of their corresponding extended surfaces but, in the case of the Pt(5,3) nanotube, a significant improvement in the activity is found when compared with the extended surfaces. In fact, the calculations predict the water dissociation to be spontaneous on Pt(5,3) with a low activation energy barrier. The platinum doping of gold and copper nanotubes leads to contrasting effects, i.e., with a slight increase of activity found on gold and a slight decrease of activity in the case of copper. The consideration of a Brönsted-Evans-Polanyi (BEP) relationship to estimate the activation energy barriers for the O-H bond break leads to a satisfactory agreement between estimated and explicitly calculated values which suggests the validity of the BEP relationship for qualitative predictions of the activities of metal nanotubes towards the water dissociation reaction.

Effects of CO2 on the deactivation behaviors of Co/Al2O3 and Co/SiO2 in CO hydrogenation to hydrocarbons

Different deactivation behaviors of the prototype Co/γ-Al₂O₃ (CoAl) and Co/SiO₂ (CoSi) catalysts under an excess CO₂ environment were investigated in terms of the surface oxidation and aggregation of cobalt crystallites for the Fischer–Tropsch Synthesis (FTS) reaction.

Catalytic Reforming of Oxygenates: State of the Art and Future Prospects

This Review describes recent advances in the design, synthesis, reactivity, selectivity, structural, and electronic properties of the catalysts for reforming of a variety of oxygenates (e.g., from simple monoalcohols to higher polyols, then to sugars, phenols, and finally complicated mixtures like bio-oil). A comprehensive exploration of the structure-activity relationship in catalytic reforming of oxygenates is carried out, assisted by state-of-the-art characterization techniques and computational tools. Critical emphasis has been given on the mechanisms of these heterogeneous-catalyzed reactions and especially on the nature of the active catalytic sites and reaction pathways. Similarities and differences (reaction mechanisms, design and synthesis of catalysts, as well as catalytic systems) in the reforming process of these oxygenates will also be discussed. A critical overview is then provided regarding the challenges and opportunities for research in this area with a focus on the roles that systems of heterogeneous catalysis, reaction engineering, and materials science can play in the near future. This Review aims to present insights into the intrinsic mechanism involved in catalytic reforming and provides guidance to the development of novel catalysts and processes for the efficient utilization of oxygenates for energy and environmental purposes.

MWCNTs as a catalyst in oxy-steam reforming of methanol

The catalytic activity of multi-walled carbon nanotubes (MWCNTs) in oxy-steam reforming of methanol (ASRM) was investigated for the first time.

The effect of carbon monoxide Co-adsorption on Ni-catalysed water dissociation

The effect of carbon monoxide (CO) co-adsorption on the dissociation of water on the Ni(111) surface has been studied using density functional theory. The structures of the adsorbed water molecule and of the transition state are changed by the presence of the CO molecule. The water O-H bond that is closest to the CO is lengthened compared to the structure in the absence of the CO, and the breaking O-H bond in the transition state structure has a larger imaginary frequency in the presence of CO. In addition, the distances between the Ni surface and H2O reactant and OH and H products decrease in the presence of the CO. The changes in structures and vibrational frequencies lead to a reaction energy that is 0.17 eV less exothermic in the presence of the CO, and an activation barrier that is 0.12 eV larger in the presence of the CO. At 463 K the water dissociation rate constant is an order of magnitude smaller in the presence of the CO. This reveals that far fewer water molecules will dissociate in the presence of CO under reaction conditions that are typical for the water-gas-shift reaction.

Methanol conversion over a Pd5Cu/Al2O3-CeO2 catalyst: an FT-IR study and reaction mechanism

A catalyst composed of a Pd(5)Cu mixed oxide supported over Al(2)O(3)-CeO(2) with general formula Pd(5)CuO(x)/Al(2)O(3)-CeO(2) (Al/Ce atomic ratio=1/1) has been prepared by a wet impregnation method and tested in the methanol conversion. The structural and morphological characterization of the catalyst evidences that it is a mesoporous material thermally stable up to 873 K. At that temperature the specific surface area value is 170 m(2)/g, and a CeO(2) cubic phase is identified together with ill-defined diffraction peaks tentatively assigned to Cu-Pd clusters, suggesting that the active phase is well dispersed over the support. Infrared studies prove that methanol conversion takes place over the catalyst to a high extent yielding syngas as main product in the range 473-723 K and methane at higher temperatures. Oxygenated intermediates containing methoxy, carbonile or formiate species are not detected, which evidences that methanol conversion to methane very probably takes place according to a via-carbide mechanism.