Methanol Synthesis Catalyst Research Articles

N,P,S-codoped C@nano-Mo2C as an efficient catalyst for high selective synthesis of methanol from CO2 hydrogenation

With the protic ionic liquid consisting of N-butylimidazolium molybdophosphate and N-butylimidazolium p-toluenesulfonate as carbon source, molybdenum source and N,P,S-doping source, the catalysts of N,P,S-codoped C@nano-Mo2C (N,P,S-dC@Mo2C) were prepared by temperature-programmed carbonization method in a N2/H2 atmosphere. The results of X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) demonstrated that N,P,S-dC@Mo2C was successfully synthesized and the morphology of N,P,S-dC@Mo2C was characterized by transmission electron microscopy (TEM). In the hydrogenation of CO2 to form methanol, N,P,S-dC@Mo2C showed highly catalytic activity and selectivity. When the N,P,S-dC@Mo2C-1073K was employed as a catalyst, the methanol selectivity of 91% was achieved with CO2 conversion of 19%. Moreover, the N,P,S-dC@Mo2C-1073K catalyst showed the excellent stability and its catalytic activity and selectivity was not decreased when the catalytic reaction was run continuously for 100h in the fixed bed reactor.

Tunability of the CO adsorption energy on a Ni/Cu surface: Site change and coverage effects.

The adsorption energy of carbon monoxide on Ni ad-islands and ultra-thin films grown on the Cu(110) surface can be finely tuned via a complex interplay among diffusion, site change mechanisms, and coverage effects. The observed features of CO desorption can be explained in terms of migration of CO molecules from Cu to Ni islands, competition between bridge and on-top adsorption sites, and repulsive lateral adsorbate-adsorbate interactions. While the CO adsorption energy on clean Cu(110) is of the order of 0.5 eV, Ni-alloying allows for its controlled, continuous tunability in the 0.98-1.15 eV range with Ni coverage. Since CO is a fundamental reactant and intermediate in many heterogeneous catalytic (electro)-conversion reactions, insight into these aspects with atomic level detail provides useful information to potentially drive applicative developments. The tunability range of the CO adsorption energy that we measure is compatible with the already observed tuning of conversion rates by Ni doping of Cu single crystal catalysts for methanol synthesis from a CO2, CO, and H2 stream under ambient pressure conditions.

Reduction of carbon dioxide via catalytic hydrogenation over copper-based catalysts modified by oyster shell-derived calcium oxide

This research aims to investigate the effects of CaO and modified CaO on copper-based catalysts for methanol synthesis. The CaO and modified CaO were derived from oyster shell and employed as an additive in a zirconia-supported copper catalyst (Cu/ZrO2). The physical and chemical properties of the catalysts were characterized by XRD, BET, CO2-TPD, H2-TPD and XANES. The addition of oyster shell-derived calcium oxide promoters to the catalysts significantly improved their chemical properties and methanol synthesis possibly owing to impurities and defects in the crystal structure of natural calcium oxide.

Direct synthesis of dimethyl ether from synthesis gas: Experimental study and mathematical modeling

Direct synthesis of dimethyl ether (DME) from syngas, was investigated over a CuO-ZnO-Al2O3 catalyst for methanol synthesis and a γ-Al2O3 catalyst for a methanol dehydration. On the base of mathematical modeling, thermodynamic analysis was carried out in a wide range of pressures (10–100bar) and temperatures (220–280°C) for binary mixtures (H2+CO) with an H2/CO=1–6M ratio. The influence of reaction conditions on the equilibrium content of components in the mixture was modelled. The effect of the loading method of catalysts of the methanol synthesis and its dehydration (layerwise loading, mixing) in the DME synthesis in a single reaction step on the CO conversion and the yield of DME was experimentally studied. It has been demonstrated that the layerwise combined loading with the intermediate mixed layer of CuO-ZnO-Al2O3 catalysts of the methanol synthesis and the γ-Al2O3 catalyst for the DME synthesis (2:1:2, ratio parts, i.e. two parts of the catalyst of the methanol synthesis, one part of a mixture of the catalysts and two parts of the catalyst of the methanol dehydration) allow to obtain the higher yield of DME. The effect of operating conditions (pressure, temperature, ratio H2/CO, time on stream, and catalyst stability) on the CO conversion and yield of DME was studied. The optimal conditions for loading variant 2:1:2 are: the pressure is 30bar, the temperature is 280°C and the initial ratio of H2/CO is equal to 2. At that, the CO conversion remains practically constant during 180h reaction run.

Use of tetraethylammonium bicarbonate as a precipitation agent on the preparation of coprecipitated Cu/ZnO catalysts

Cu/ZnO catalysts were prepared by coprecipitation using tetraethylammonium bicarbonate (TEA+HCO3−), and their properties and methanol synthesis activities were compared to those of the catalysts prepared using Na+HCO3− usually employed for commercial Cu/ZnO/(Al2O3) catalysts. When washed fully, TEA+- and Na+-based precursors showed typical zincian malachite (zM) without any other structures, and both catalysts obtained after calcination and H2 reduction exhibited the similar specific copper surface area and, in turn, the similar methanol productivity. Since this result explains that TEA+ does not affect zM structure if Cu,Zn precipitate is fully washed, no washed and less washed TEA+- and Na+-based precursors were prepared. It was interesting that all TEA+-based catalysts exhibited the similar methanol productivity irrespective of the washing efficiency whereas Na+-based catalyst containing more residual Na+ showed the smaller copper surface area and lower methanol productivity (i.e., linear correlation between the two parameters). This resulted from the inhibiting effect of Na+ on the degree of Cu2+ substitution by Zn2+ and the formation of high-temperature carbonate, consequently leading to a lower catalytic activity. These negative effects of Na+ were absent or lessened when TEA+HCO3− was used as a precipitation agent, which is effective in preparing an active methanol synthesis catalyst.

Evidence for support effects in metal oxide supported cobalt catalysts

Cobalt supported on a number of different metal oxides are often used in the Fischer–Tropsch (FT) reaction. No obvious rationale for the composition of the metal oxide used exists. In this paper we examine the possibility that some form of interaction between the metal and the metal oxide support exists which enhances the activity of the Co metal. To this effect, we have supported Co metal on a series of metal oxides of different degrees of reducibility: (i) Al2O3 which is unreducible under FT conditions, (ii) ZrO2 which can be reduced to a small extent under FT conditions, and (iii) ZnO which can be reduced to a measurable degree under FT conditions. The postulate was that the more reducible support will have the greater number of trapped electrons at anion vacancies, and so will have the greater possibility of transferring these electrons from the support to the metal, giving rise to a sequentially greater metal/metal oxide interaction. We have previously shown that temperature programmed desorption/decomposition of formate species adsorbed on Cu/ZnO/Al2O3 (methanol synthesis catalysts) has been able to identify adsorption sites on: (i) the Cu metal, (ii) the ZnO, (iii) Al2O3 and (iv) at the Cu/ZnO interface. Here we have used the same probe reaction, namely the adsorption and temperature programmed desorption/decomposition of a formate species, to identify and predict the extent of metal/metal oxide interaction. The whole system, the kinetics of the decomposition of the formate used, and the different forms of metal oxide support used constituted a predictive possibility of what would constitute an active metal oxide supported Co catalyst on (i) Co supported on Al2O3, on (ii) Co supported on ZrO2 and (iii) on Co supported on ZnO. The ZnO support is shown to provide the greatest extent of charge transfer from the support to the Co, evidenced by the lowest temperature for desorption/decomposition of the formate of all the supports used, and the largest amount of CO in the product spectrum. The in situ N2O reactive frontal chromatography measurement of the Co metal area showed the formate species to be closely packed on the Co.

The Effects of Secondary Oxides on Copper‐Based Catalysts for Green Methanol Synthesis

Catalysts for methanol synthesis from CO2 and H2 have been produced by two main methods: co‐precipitation and supercritical anti‐solvent (SAS) precipitation. These two methods are compared, along with the behaviour of copper supported on Zn, Mg, Mn, and Ce oxides. Although the SAS method produces initially active material with high Cu specific surface area, they appear to be unstable during reaction losing significant amounts of surface area and hence activity. The CuZn catalysts prepared by co‐precipitation, however, showed much greater thermal and reactive stability than the other materials. There appeared to be the usual near‐linear dependence of activity upon Cu specific area, though the initial performance relationship was different from that post‐reaction, after some loss of surface area. The formation of the malachite precursor, as reported before, is important for good activity and stability, whereas if copper oxides are formed during the synthesis and ageing process, then a detrimental effect on these properties is seen.

Bimetallic Pd–Cu/ZnO–Al2O3 and Pd–Cu/ZrO2–Al2O3 catalysts for methanol synthesis

Monometallic copper and bimetallic palladium-copper catalysts supported on ZnO–Al2O3 and ZrO2–Al2O3 were prepared by conventional impregnation method and tested in methanol synthesis reaction under elevated pressure (3.5 MPa) in gradientless reactor at 220°C. The physicochemical properties of prepared catalytic systems were studied using BET, X-ray, TPR-H2, TPD-NH3 techniques. The promotion effect of palladium on catalytic activity and selectivity of copper supported catalyst in methanol synthesis reaction was proven. The highest activity of this system is explained by the Pd–Cu alloy formation.

A Study on the Order of Calcination and Liquid Reduction over Cu-Based Catalyst for Synthesis of Methanol from CO2/H2

Cu/Zn/Al/Zr catalysts were prepared by liquid reduction method and tested for the synthesis of methanol by CO2 hydrogenation. With the purpose of relieving the aggregation of reduced Cu species, the order of calcination and liquid reduction process was modified. Catalysts with different thermal treatments were characterized by XRD, N2 physisorption, TEM, N2O chemisorption, TG–MS, XPS, TPR, CO2-TPD techniques. When liquid reduction was performed after calcination procedure, metallic Cu specific area and dispersion increased and the interaction among components was strengthened. The modified catalyst displays a slight superiority in CO2 conversion and methanol selectivity.

2-28 Direct synthesis of LPG from syngas over hybrid catalysts containing methanol synthesis catalyst and zeolite

2-28 Direct synthesis of LPG from syngas over hybrid catalysts containing methanol synthesis catalyst and zeolite

2-31.ソフトコンピューティングと高速スクリーニングによる触媒開発(8) : 96ウェルマイクロプレートシステムとラジアル基底関数ネットワークによるメタノール合成用Cu-Zn-Al-Ga酸化物触媒の組成最適化((10)転換利用III,Session 2 天然ガス・メタンハイドレート等)

2-31.ソフトコンピューティングと高速スクリーニングによる触媒開発(8) : 96ウェルマイクロプレートシステムとラジアル基底関数ネットワークによるメタノール合成用Cu-Zn-Al-Ga酸化物触媒の組成最適化((10)転換利用III,Session 2 天然ガス・メタンハイドレート等)

Morphology effect of nanostructure ceria on the Cu/CeO2 catalysts for synthesis of methanol from CO2 hydrogenation

Three kinds of CeO2 with different nanostructures were prepared by a controlled hydrolysis method, and Cu/CeO2 catalysts were prepared by an incipient wetness impregnation method. The catalytic activity of Cu/CeO2 catalysts was evaluated by the methanol synthesis from CO2 hydrogenation. It was observed that the support morphology greatly affected the activity and selectivity of methanol synthesis from CO2 hydrogenation. The nanorod CeO2 supported Cu/CeO2 catalyst by the exposure of (100) and (110) faces showed the strongest interaction between CuO and CeO2, highest CuO dispersion and the highest catalytic activity with methanol yield of 1.9% at 240°C and 2MPa.

Production of Light Hydrocarbons from Syngas Using a Hybrid Catalyst

A hybrid catalyst consisting of a Cu-ZnO/Al2O3 methanol synthesis catalyst and a SAPO-34 molecular sieve was shown to convert syngas into a narrow mixture of short chain paraffins centered at C2–C3 with little methane and C5+ made. This product mix is expected to be an excellent cracker feedstock for the production of olefins. The hybrid catalyst system closely couples sequential reactions on each of the two independent catalysts. The function of each of the components was unraveled by performing experiments in which the reactor was loaded with discrete layers of the individual catalysts. Methanol (MeOH) synthesis over Cu-ZnO/Al2O3 is followed by methanol conversion to dimethyl ether (DME) + steam over the acidic SAPO-34 or Cu-ZnO/Al2O3 component. Simultaneously, the so generated water feeds into the water gas shift (WGS) reaction over Cu-ZnO/Al2O3, producing H2 + CO2, and the DME/MeOH undergoes methanol to olefins (MTO) conversion over SAPO-34. The olefins are subsequently hydrogenated to paraffins over ...

Bifunctionality of Cu/ZnO catalysts for alcohol-assisted low-temperature methanol synthesis from syngas: Effect of copper content

Alcohol-assisted low-temperature methanol synthesis was conducted over Cu/ZnO_X catalysts while varying the copper content (X). Unlike conventional methanol synthesis, ethanol acted as both solvent and reaction intermediate in this reaction, creating a different reaction pathway. The formation of crystalline phases and characteristic morphology of the co-precipitated precursors during the co-precipitation step were important factors in obtaining an efficient Cu/ZnO catalyst with a high dispersion of metallic copper, which is one of the main active sites for methanol synthesis. The acidic properties of the Cu/ZnO catalyst were also revealed as important factors, since alcohol esterification is considered the rate-limiting step in alcohol-assisted low-temperature methanol synthesis. As a consequence, bifunctionality of the Cu/ZnO catalyst such as metallic copper and acidic properties was required for this reaction. In this respect, the copper content (X) strongly affected the catalytic activity of the Cu/ZnO_X catalysts, and accordingly, the Cu/ZnO_0.5 catalyst with a high copper dispersion and sufficient acid sites exhibited the best catalytic performance in this reaction.

Catalyst Deactivation During One-Step Dimethyl Ether Synthesis from Synthesis Gas

Catalysts for direct synthesis of dimethyl ether (DME) from synthesis gas should essentially contain two functions, i.e., methanol synthesis and methanol dehydration. In the present work, the deactivation of both functions of hybrid catalysts during direct DME synthesis under industrially relevant conditions has been investigated with special focus on the influence of each reaction step on the deactivation of the catalyst function corresponding to the other step. A physical mixture of a Cu–Zn-based methanol synthesis catalyst and a ZSM-5 methanol dehydration catalyst was used. The metallic catalyst appears to deactivate due to Cu sintering, with no apparent effect from the methanol dehydration step under the conditions applied. The acid catalyst deactivates due to accumulation of hydrocarbon species formed in its pores. Synthesis gas composition, i.e., $$\text{{H}}_{2}$$ /CO ratio and $$\text{{CO}}_{2}$$ -content (which directly affects partial pressure of water), seems to influence the zeolite deactivation.

Methanol synthesis catalyst manufacturing using the green solid-state method

In this research study, methanol synthesis catalysts were manufactured with various mole ratios of metal carbonates (zinc, copper and aluminum carbonate) and ammonium hydrogen carbonate via a green solid-state method that employed a ball mill apparatus. Some parameters for the catalyst preparation, such as Al mole percent, Cu/Zn mole ratio, rotations milling speeds and aging time, were optimized to obtain the maximum catalyst activity. The prepared catalysts were compared with the best quality industrial catalyst under the same temperature and pressure condition in a titanium tabular fixed bed reactor. This novel method has many advantages in comparison to the conventional method. The main advantage of the solid-state method is that the methanol synthesis catalyst can be produced without using solvent. Furthermore, this new method reduces operating costs due to the elimination of the filtration and washing steps. Methanol synthesis catalytic activity was maximized at an optimized mole ratio of Cu/Zn of 1.9234 and an Al mole percent of 8 at the maximum grinding speed (450 rpm) during an aging time of 30 min, which showed higher activity (240 gCH3OH/kg cat.h) in comparison with an industrial catalyst sample (218 gCH3OH/kg cat.h). The production of a green catalyst, which requires less water and results in higher catalyst activity, can be widely used for methanol synthesis catalytic applications.

Status and prospects in higher alcohols synthesis from syngas.

Higher alcohols are important compounds with widespread applications in the chemical, pharmaceutical and energy sectors. Currently, they are mainly produced by sugar fermentation (ethanol and isobutanol) or hydration of petroleum-derived alkenes (heavier alcohols), but their direct synthesis from syngas (CO + H2) would comprise a more environmentally-friendly, versatile and economical alternative. Research efforts in this reaction, initiated in the 1930s, have fluctuated along with the oil price and have considerably increased in the last decade due to the interest to exploit shale gas and renewable resources to obtain the gaseous feedstock. Nevertheless, no catalytic system reported to date has performed sufficiently well to justify an industrial implementation. Since the design of an efficient catalyst would strongly benefit from the establishment of synthesis-structure-function relationships and a deeper understanding of the reaction mechanism, this review comprehensively overviews syngas-based higher alcohols synthesis in three main sections, highlighting the advances recently made and the challenges that remain open and stimulate upcoming research activities. The first part critically summarises the formulations and methods applied in the preparation of the four main classes of materials, i.e., Rh-based, Mo-based, modified Fischer-Tropsch and modified methanol synthesis catalysts. The second overviews the molecular-level insights derived from microkinetic and theoretical studies, drawing links to the mechanisms of Fischer-Tropsch and methanol syntheses. Finally, concepts proposed to improve the efficiency of reactors and separation units as well as to utilise CO2 and recycle side-products in the process are described in the third section.

Local structural evolutions of CuO/ZnO/Al2O3 catalyst for methanol synthesis under operando conditions studied by in situ quick X-ray absorption spectroscopy

In situ quick X-ray absorption spectroscopy (QXAFS) at the Cu and Zn K-edge under operando conditions has been used to unravel the Cu/Zn interaction and identify possible active site of CuO/ZnO/Al2O3 catalyst for methanol synthesis. In this work, the catalyst, whose activity increases with the reaction temperature and pressure, was studied at calcined, reduced, and reacted conditions. TEM and EDX images for the calcined and reduced catalysts showed that copper was distributed uniformly at both conditions. TPR profile revealed two reduction peaks at 165 and 195 °C for copper species in the calcined catalyst. QXAFS results demonstrated that the calcined form consisted mainly of a mixed CuO and ZnO, and it was progressively transformed into Cu metal particles and dispersed ZnO species as the reduction treatment. It was demonstrated that activation of the catalyst precursor occurred via a Cu+ intermediate, and the active catalyst predominantly consisted of metallic Cu and ZnO even under higher pressures. Structure of the active catalyst did not change with the temperature or pressure, indicating that the role of the Zn was mainly to improve Cu dispersion. This indicates the potential of QXAFS method in studying the structure evolutions of catalysts in methanol synthesis.

Surface Alloy or Metal–Cation Interaction‐The State of Zn Promoting the Active Cu Sites in Methanol Synthesis Catalysts

AbstractModel catalysts containing disordered CuO and ZnO species in the pores of SBA‐15 were reduced under different conditions (standard: H2, 513 K; severe: CO/H2, 673 K), studied by X‐ray diffraction (XRD) and X‐ray absorption spectroscopy (XAS) including operando work and used as catalysts for methanol synthesis at pressures up to 8 bar, where they were comparable with a commercial reference in terms of reaction rates related to Cu surface area. Severe reduction caused significant activation of the Cu sites beyond the sizeable level achieved already after standard reduction. In XRD, which failed to detect most of the active components, owing to small particle sizes, weak indications of alloy formation were found after severe reduction. XAFS, which averages over all species present, showed the interaction of Cu with zinc ions to increase by severe reduction, while formation of Zn0 was below detection limit. On this basis, the promoting interaction of Zn to Cu was ascribed to an interaction of zinc cations with Cu0.

RECYCLING OF CARBONE OXIDES (CO, CO2) CONVERSION INTO METHANOL AT ATMOSPHERIC PRESSURE OVER MECHANOCHEMICAL ACHTIVATED CUO-ZNO-AL2O3 CATALYST

The catalytic process for methanol production by synthesis gas conversion under the conditions of mechanochemical activation (MCA) of copper-zinc-aluminum oxide catalyst in the temperature range 160–280 °C at a pressure of 0.1 MPa are investigated. The use of mechanical action force is one of the promising ways to improve the activity of heterogeneous catalysts designed to simplify the manufacturing process lines, improving the efficiency of catalytic processes and reduce the cost of the target product. Given the importance of technology for methanol production on copper-zinc-aluminum oxide catalysts and high demand for methanol in the world [1–3], clarification of the peculiarities of the process of methanol production by synthesis gas conversion in terms of mechanical load on the catalyst is important in scientific and applied ways. It is established that specific catalytic activity, performance of methanol synthesis catalyst and the conversion of initial reagents are increased in the conditions of mechanochemical activation, because of the increasing concentration of defects and formation of additional active centers. It is revealed that mechanochemical treatment of copper-zinc-aluminum oxide catalyst can reduce reaction initiation temperature and optimum temperature synthesis by 20–30 °C, and increase the maximum performance of the catalytic system. Increase of the catalyst activity under mechanical stress is explored by increase of defect concentration of crystal lattice of the catalyst, as confirmed by the tests of catalyst surface structure by scanning electron microscopy, Raman spectroscopy and X-ray analysis. A new effective method for synthesis gas conversion into the methanol under conditions of mechanochemical activation of the catalyst can be used in industry as an alternative to methanol production at high pressures.