Effect of Al loading on the catalytic performance of Cu/ZnO catalysts in methanol production from biomass pyrolysis syngas

Alcohol Production from Carbon Dioxide: Methanol as a Fuel and Chemical Feedstock

Process and sustainability analyses of the integrated biomass pyrolysis, gasification, and methanol synthesis process for methanol production

Chapter 5 - Technological advancements in biofuel, bioproducts, and bioenergy production from fast pyrolysis of lignocellulosic biomass

By utilizing greenhouse gas CO2 and renewable energy-sourced H2 to produce methanol, the “methanol economy” can replace fossil fuels and H2 as the energy storage medium, which not only reduces CO2 emissions, but also mitigates the energy shortage issue. However, the traditional Cu-based catalysts for CO2-to-methanol conversion suffer from low activity at low temperature and high vulnerability to sintering and deactivation. In this contribution, rapidly quenched skeletal Cu catalysts (RQ Cu) are prepared by leaching the RQ Cu–Al alloy with NaOH aqueous solutions of different concentrations. It is found that high NaOH concentration of 10 wt% favors the preparation of the RQ Cu-10 catalyst with higher porosity, lower residual Al content, and larger active Cu surface area (SCu) than the RQ Cu-3 catalyst leached with 3 wt% of NaOH solution. However, in aqueous-phase CO2 hydrogenation at 473 K and 4.0 MPa, the CO2 conversion over the RQ Cu-3 catalyst is more than two times greater than that over the RQ Cu-10 catalyst, and the selectivity and productivity of methanol are 1.20 and 2.69 times of the corresponding values over the RQ Cu-10 catalyst. At 5.0 MPa, the selectivity and productivity of methanol are further boosted to 97.9% and 1.329 mmol gCu–1 h–1 on the RQ Cu-3 catalyst. It is identified that the SCu of the RQ Cu-3 catalyst is well preserved after reaction, while dramatic growth of the Cu crystallites occurs for the RQ Cu-10 catalyst. The better catalytic performance and stability of the RQ Cu-3 catalyst are tentatively attributed to the presence of more residual Al species by using NaOH solution with lower concentration for Al leaching, which acts as the dispersant for the Cu crystallites during the reaction.

Correlations between synthesis, precursor, and catalyst structure and activity of a large set of CuO/ZnO/Al 2O 3 catalysts for methanol synthesis

In terms of supplying energy carriers for the transport sector and storing electricity outflows from intermittent sources, the importance of renewable fuel production has become significant. In this work, the production of methanol fuel from biomass is simulated. Biomass is an excellent renewable resource for the production of methanol. It is of utmost importance to make effective use of biomass resources. There are different methods available for the production of methanol from biomass. One of the best methods is pyrolysis to convert biomass into methanol. This is due to the fact that pyrolysis is an efficient conversion method compared to other thermochemical conversion practices. Pyrolysis is the process of decomposing biomass in an inert atmosphere to convert it into worthwhile products. The production of methanol from sugarcane bagasse via pyrolysis was simulated using Aspen HYSYS because of its ability to solve chemical as well as energy problems. To simulate the microwave assisted pyrolysis reactor, an Aspen HYSYS model was developed. The model is based on Gibbs free energy and it has been calibrated using the restricted equilibrium method. The model was validated and foresees the percentage of methanol yield, the predicted values very well agreed with the available data. Important parameters of the pyrolysis process such as pyrolysis temperature, sweeping nitrogen gas flow rate, heating rate, biomass moisture content were varied. It was found that pyrolysis temperature, nitrogen flow rate, heating rate have a very profound influence on the pyrolysis process and methanol yield, while the moisture content of biomass had a lesser impact.

Cu-based catalysts are widely employed for CO or CO2 hydrogenation into methanol. However, their catalytic performance highly depends on supports, and the real evolution of Cu species is still covered by active components. Herein, we supply a Cu/SiO2 catalyst prepared by flame spray pyrolysis (FSP), showing catalytic performance comparable to that of the active Cu/ZrO2 catalyst for methanol synthesis from CO2. It reaches 79% selectivity at a CO2 conversion of 5.2%, which is an outstanding selectivity among previously reported Cu/SiO2 catalysts, considering they are generally treated as nearly inert catalysts. In situ X-ray absorption spectroscopy (XAS) analysis shows that 5 times more Cu+ species in the FSP-Cu/SiO2 are stabilized in comparison to those in the traditional ammonia evaporation (AE) made catalyst even after reduction at 350 °C. A unique shattuckite-like precursor with a slightly distorted Cu–O–Si texture structure formed in the FSP-made catalyst is responsible for the enriched Cu+ species. Variations of intermediate formation and methanol production are found to have a good relationship with the amount of Cu+ species. According to the results of high-pressure in situ DRIFTS, we attribute this to the promotional effect of Cu+ on the stabilization of CO* intermediates, which inhibits CO desorption and facilitates further hydrogenation to CH3OH via the RWGS + CO-Hydro pathway. These results bring insights into the Cu reduction behavior and the function of Cu+ species during methanol production on Cu-based catalysts without the assistance of active supports.

Molecular catalysts immobilized on a carbon support have demonstrated electrocatalytic CO2 conversion capabilities distinct from those of metallic surfaces. For instance, cobalt phthalocyanine supported on carbon nanotubes (CoPc/CNT) is capable of selective CO2-to-methanol conversion with ∼30% selectivity, which cannot be accomplished by other metal catalysts, such as cobalt, silver, and copper. However, despite its promising methanol selectivity, the CoPc/CNT catalyst exhibits a gradual decrease in the methanol production rate during the electrochemical CO2 reduction reaction (CO2RR). This catalytic instability impedes its practical application, yet little is known about the origin of the activity decay and viable solutions to circumvent it. In this study, we show that the catalytic deactivation is not an irreversible process caused by the chemical degradation of the catalyst and present reactivation strategies to recover the catalytic performance for stable methanol production. We propose that formaldehyde, an intermediate generated during the CO2RR, can act as a poisoning species, and its adsorption configuration on the cobalt site can determine the fate of its reaction pathway: carbon-down (*CH2O) versus oxygen-down (*OCH2) pathways. In contrast to the carbon-down configuration leading to methanol production, the oxygen-down configuration can inhibit its further reduction, poisoning the cobalt active site and causing the deactivation.

The process of preparing methanol from carbon dioxide is one of the ways to solve the environmental problems caused by greenhouse gases, the problem of fossil energy depletion, and the problem of fuel exhaust emissions. However, after decades of development, the process of preparing methanol from carbon dioxide is still unable to achieve large‐scale industrialization. This critical review sharply points out the problems and obstacles that need to be solved urgently on the industrialization road of carbon dioxide methanol preparation process and summarizes its progress. The problems faced by the methanol production industry from carbon dioxide are first the thermodynamic constraints, second the lower reaction rate and conversion effect, and finally the energy loss. In order to solve these problems, this paper first introduces the active sites, structural effects, and dynamic changes of copper‐based catalysts, as well as the unique reaction mechanism and doping modification of indium‐based catalysts. Zinc and zirconium promoters and some metal oxide supports can form unique interactions with active components to improve the catalytic performance of the catalyst. Next, various kinetic models and applications of methanol production from carbon dioxide are summarized, which is an important bridge linking laboratory and industrialization; the advantages and disadvantages of fixed bed reactor and paddle reactor were compared. Finally, the full text is summarized and prospected.

The application of ZnO–ZrO2-based oxide catalysts in the CO2-to-methanol hydrogenation reaction has garnered significant attention; yet, insights into the active site configurations and reaction mechanism remain elusive. In this study, by employing advanced solid-state NMR techniques, we comprehensively investigated the surface active sites and the activation of CO2 and H2 molecules on the ZnZrOx solid-solution catalyst, complemented by comparative investigations on supported ZnO/ZrO2 catalysts. We revealed the intricate surface structure of the ZnZrOx solid-solution catalyst at the atomic level, highlighting the presence of a disordered surface ZnO phase and the Zn–OH–Zr interface, as identified by 17O MAS NMR. Notably, the ZnZrOx solid-solution and supported ZnO/tetragonal-ZrO2 catalysts exhibit strikingly similar surface features, correlating with their comparable catalytic performances. A key breakthrough is the direct identification of active bidentate carbonate species formed through the CO2 interaction with surface oxygen vacancies, specifically at the Zn–[Ov]–Zr interface. Using trimethylphosphine as a probe molecule, the relationship between oxygen vacancies and methanol production was confirmed by 31P NMR. More importantly, NMR analysis provides the direct evidence on the formation of surface zinc hydride (Zn–H) over both ZnZrOx solid-solution and supported ZnO/ZrO2 catalysts during H2 activation. These Zn–H species, in close proximity to oxygen vacancies, are shown to readily activate CO2 even at room temperature, leading to the formation of a surface formate intermediate and thereby facilitating methanol production. This study offers fundamental atomic-level insights into the critical surface active sites and reaction mechanism underlying CO2 hydrogenation on the ZnO–ZrO2-based catalysts, and also paves the way for the rational design of more efficient catalysts for methanol production.

A series of water‐soluble arene‐Ru(II) complexes, [(η6‐p‐cymene)RuCl(L)]+Cl‒ ([Ru]‐7 – [Ru]‐12) (L = substituted bis‐imidazole methane) exhibited efficient and selective methanol production from paraformaldehyde in water. The findings inferred a crucial role of the ligand in tuning the catalytic performance. A pH‐dependent behavior of this series of catalysts was observed, where the amount of base was influential in methanol production from paraformaldehyde. The catalyst [Ru]‐7 (L1 = 4,4′‐((2‐hydroxyphenyl)methylene)bis(2‐ethyl‐5‐methyl‐1H‐imidazole) was the most efficient among the explored catalysts giving a turnover number (TON) of 1200 at 90 °C. A mechanistic cycle has also been proposed for the catalytic reaction based on the mass and NMR investigations including those using deuterium‐labelled molecules.

In recent years, the monolithic material has been developed increasingly in the high performance liquid phase field, and it could also be applied in the field of catalyst, as a monolithic catalyst carrier, since it has a large specific surface area, and could be customized based on the mould. The monolithic catalyst is characterized with many advantages such as low bed pressure, high physical efficiency and small amplification effect. The most impotant part refers to the preparation of copper-based catalyst. The impregnation method is used to produce CuO-ZnO monolithic catalyst and CuO-ZnO-ZrO2 monolithic catalyst with the prepared monolithic silica-alumina carrier. The fixed bed microreactor is used to investigate the effect of copper-based catalyst on the process in which carbon dioxide is used to produce methanol through hydrogenation. The metal salt is added into the sol-gel process, which could form the M-O-Si bond, thus make the metal-containing catalytic material obtain good mechanical strength, and make it possible to be introduced into the acidic center generally. The metal-containing catalytic material carrier also has macropores and mesopores. The presence of large pores could make the molecular mass transfer more effective, while the presence of mesopores could increase the specific surface area of the material. In this paper, the experimental study has been conducted on the production of methanol through hydrogenation of CO2 under different catalysts, to mainly investigate the effect of catalysts with different catalytic performance on the reaction.

The Cu‐based catalysts have been widely employed in the hydrogenation of CO2‐derived ethylene carbonate (EC) to ethylene glycol (EG) and other derivatives, but still suffered from some problems such as unsatisfactory selectivity and catalyst stability. Herein, a Cu@MIL‐101 catalyst was prepared via a two‐solvent method to anchor copper (Cu) nanoparticles into the MIL‐101 metal organic frameworks, which exhibited superior catalytic performance with ∼100% conversion, 2‐hydroxyethyl formate (2‐HEF) selectivity of 82% at 160°C, or EG selectivity of ∼92% at 180°C. The characterization results showed that the Cu0 and Cr3+ species play a key role on the dissociation of H2 and activation of C‐O and C=O bonds in the esters, and thus exhibited an excellent catalytic performance of the EC hydrogenation. In addition, the strong interaction between Cu0 species and unsaturated coordination Cr3+ species in the MIL‐101 framework resulted in the high stability. Since the product of methanol was not generated on the Cu@MIL‐101 catalyst, it is valuable to produce 2‐HEF by controlling the temperature of 160°C in the EC hydrogenation rection. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd.

Liquid fuels obtained from CO2 and green hydrogen (i.e., e-fuels) are powerful tools for decarbonizing economy. Improvements provided by Process Intensification in the existing conventional reactors aim to decrease energy consumption, increase yield, and ensure more compact and safe processes. This review describes the advances in the production of methanol, dimethyl ether, and hydrocarbons by Fischer–Tropsch using different Process Intensification tools, mainly membrane reactors, sorption-enhanced reactors, and structured reactors. Due to the environmental interest, this review article focused on discussing methanol and dimethyl ether synthesis from CO2 + H2, which also represented the most innovative approach. The use of syngas (CO + H2) is generally preferred for the Fischer–Tropsch process; hence, studies examining this process were included in the present review. Both mathematical models and experimental results are discussed. Achievements in the improvement of catalytic reactor performance are described. Experimental results in membrane reactors show increased performance in e-fuels production compared to the conventional packed bed reactor. The combination of sorption and reaction also increases the single-pass conversion and yield, although this improvement is limited by the saturation capacity of the sorbent in most cases.

Preparation and catalytic properties of copper-ytterbium oxide system for CO hydrogenation