Chalachew Mebrahtu Asmelash

RWTH Aachen University · Institute for Technical und Macromolecular Chemistry

ChatGPT is an AI language model trained on vast amounts of text data, including scientific papers, providing a comprehensive understanding of catalysis. However, its reliability in catalysis research is unknown. To evaluate reliability, we compared a ChatGPT-generated review article on heterogeneous catalysts for higher alcohols synthesis by CO2 hy...

CO2 hydrogenation to ethanol presents an important way to reduce CO2 emissions and mitigate global warming. Since the solvent plays a key role in this reaction (i. e. in a batch reactor), the thermodynamics is investigated herein using an RGibbs model in Aspen Plus to illustrate the effects of solvents with various dielectric constant and vapor pre...

Synthesis of higher alcohols by CO2 hydrogenation is a promising way to mitigate CO2 emissions, meanwhile producing value-added fuels and chemicals. However, CO2 hydrogenation to higher alcohols is kinetically hindered and due to the absence of highly efficient catalysts, its industrial implementation is still limited. Among the catalysts designed...

Titania supported MoOx catalysts containing varying surface densities of Mo were prepared and well-characterized to identify the most effective MoOx species for the deoxydehydration (DODH) reaction of 1,4-anhydroerythritol (1,4-AHE), and...

Renewable H2 production by water electrolysis has attracted much attention due to its numerous advantages. However, the energy consumption of conventional water electrolysis is high and mainly driven by the kinetically inert anodic oxygen evolution reaction. An alternative approach is the coupling of different half‐cell reactions and the use of red...

Renewable H2 production by water electrolysis has attracted much attention due to its numerous advantages. However, the energy consumption of conventional water electrolysis is high and mainly driven by the kinetically inert anodic oxygen evolution reaction. An alternative approach is the coupling of different half‐cell reactions and the use of red...

Synthesis of higher alcohols (C2-4OH) by CO2 hydrogenation presents a promising way to convert CO2 into value-added fuels and chemicals. Understanding the thermodynamics of CO2 hydrogenation is of great importance to tailor the reaction network toward synthesis of higher alcohols; however, the thermodynamic effects of various alcohol isomers and me...

Stabilization of single metal atoms is a persistent challenge in heterogeneous catalysis. Especially supported late transitions metals are prone to undergo agglomeration to nanoparticles under reducing conditions. In this study, nitrogen‐rich covalent triazine frameworks (CTFs) are used to immobilize iridium complexes. Upon reduction at 400°C, immo...

Recently, H2 has attracted increasing attention as green energy carrier holding the possibility to replace fossil fuel-based energy sources and thereby reduce CO2 emissions. Green hydrogen can be generated by water electrolysis using renewable energies like wind and solar power. When it is combusted, only water forms as by-product. However, the eff...

Feed composition is crucial for gas-phase catalytic reactions but has rarely been studied in CO2 methanation. In this work, we studied the effect of impurities (i.e., N2, steam, and O2) on the activity of Ni/ZrO2 in CO2 methanation. The reducible ZrO2 favored the formation of oxygen vacancies, which enhanced CO2 adsorption and subsequent hydrogenat...

The design of advanced catalysts for CO2 methanation remains as a research challenge. Besides, the effects of feed composition on the activity and stability of existed catalysts are not well addressed yet. In this work, novel A2BO4-type catalysts derived from La2-xCexNiO4 perovskites are reported for CO2 methanation. The reduced La0.5Ce1.5NiO4 (r-L...

Cu/SiO2 catalysts prepared by a deposition-decomposition (DD) method using ammonium hydroxide are currently among the most promising catalysts for oxalates hydrogenation to ethylene glycol (EG). Here, a Cu/SiO2 catalyst prepared by the DD method was pre-reduced at a) 200 - 350 °C in 100% H2, and 2) 200°C in a 50% H2/N2 mixture. Then, it was tested...

A hierarchical methodology for process design and evaluation reveals how the remarkable achievements in catalyst development for dimethoxymethane (DMM) synthesis can make DMM a sustainable future e-fuel.

The concept of an integrated power‐to‐gas (P2G) process was demonstrated for renewable energy storage by converting renewable electrical energy to synthetic fuels. Such a dynamically integrated process enables direct production of Synthetic Natural Gas (SNG) from CO2 and H2O. The produced SNG can be stored or directly injected into the existing nat...

Global warming due to the accumulation of atmospheric CO2 has received great attention in recent years. Hence, it is urgent to reduce CO2 emissions into the atmosphere and develop sustainable technologies for a circular carbon economy. In this regard, CO2 capture coupled with the conversion into chemicals and fuels provides a promising solution to...

Oxymethylene ethers (OMEs) are synthetic fuels with excellent ability in reducing soot formation and good compatibility for diesel engines. Among OMEs, dimethoxymethane (DMM) is the simplest compound and its conventional production relies on an oxidative route leading to low H2 efficiency. Hence, recently, our group presented a H2 efficient gas-pha...

Dimethoxymethane (DMM), a promising synthetic fuel enabling clean combustion, is usually produced by condensation of methanol and formaldehyde, where the latter stems from methanol oxidation. Here, we report the hydrogen efficient non-oxidative DMM synthesis over a bifunctional Cu/zeolite catalyst in a continuous gas-phase fixed bed reactor. Methan...

Hydrotalcite-derived Ni and Fe-promoted hydrotalcite-derived Ni catalysts were found to outperform industrial catalysts in the CO2 methanation reaction, however the origin of the improved activity and selectivity of these catalysts is not clear. Here, we report a study of these systems by means of in situ X-ray photoelectron spectroscopy and near-e...

Metal oxide supported Ni-based catalysts represent intensively studied materials for CO2 methanation due to their relatively high activity, methane selectivity and low cost. However, the activity of Ni-based catalysts mainly depends on the nature of the used support during catalyst synthesis. Due to their good performance, hydrotalcite derived Mg–A...

When using undiluted H2 + CO2 feeds in stoichiometric ratios, it is necessary to use a reactor outlet temperature below about 320 °C in CO2 methanation in order to achieve equilibrium conditions which allow the specifications of natural gas to be met. Under these conditions, a deactivation mechanism different from that reported for higher temperatu...

The power to gas (P2G) process has the potential to solve long-term and large-scale energy storage problems as well as reduce CO 2 emissions. P2G involves CO 2 methanation as a pillar of the process for the production of synthetic natural gas. Therefore, this chapter focuses on the principles and fundamental challenges of the CO 2 methanation. In C...

The catalytic performance of a Ni/Al hydrotalcite derived catalyst for CO2 methanation was analysed under different operating conditions. The as synthesized sample has been characterized through atomic adsorption spectroscopy (AAS) X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, temperature programmed reduction (TPR) and CO chemisor...

It is essential for mankind to address greenhouse gas emission, depletion of fossil resources and development of efficient storage and transportation of renewable energy. By using the atmospheric gas CO2 as raw material for the value-added chain, an overall CO2 neutral circular economy is imaginable. The power to gas (PtG) concept tackles all three...

Nanosheet-type catalysts were synthesized via a two-step hydrothermal method and characterized by several physicochemical methods. Catalytic activity in CO2 methanation was investigated in the 300-350°C temperature range and pressure of 5 bar. A high activity at 300°C (about 860 molCH4 molNi-1 h-1) and 99% of CH4 selectivity with a stable catalytic...

Nanocomposites of Zn-Ti-Fe oxide using zinc as a host with different ratios of precursor salts were prepared by co-precipitation method to use as semiconductors for dye sensitized solar cell (DSSC). The as-synthesized nanocomposites were characterized using XRD, SEM-EDX, TEM and UV-Vis spectrophotometer. DSSCs based on the new semiconductors and di...

Methanation of CO2 was studied in a high throughput reactor (Amtech SPIDER 16) over Ni catalysts supported on ternary and quaternary alumina-zirconia-titania-ceria mixed oxides, in order to compare them under industrial relevant conditions and derive indications about the structure-activity relationships and specifically the role of ceria. The samp...

Fe2O3-CNT samples are studied for the room temperature electrocatalytic synthesis of NH3 from H2O and N2 in a gas-liquid-solid three-phase reactor. A 30% wt iron-oxide loading was found to be optimal. The performances greatly depend on the cell design, where the possibility of ammonia crossover through the membrane has to be inhibited. The reaction...

Ammonia is synthesized directly from water and N2 at room temperature and atmospheric pressure in a flow electrochemical cell operating in gas phase (half-cell for the NH3 synthesis). Iron supported on carbon nanotubes (CNTs) was used as the electrocatalyst in this half-cell. A rate of ammonia formation of 2.2×10−3 g m−2 h−1 was obtained at room te...

Ammonia is synthesized directly from water and N2 at room temperature and atmospheric pressure in a flow electrochemical cell operating in gas phase (half-cell for the NH3 synthesis). Iron supported on carbon nanotubes (CNTs) was used as the electrocatalyst in this half-cell. A rate of ammonia formation of 2.2×10−3 g m−2 h−1 was obtained at room te...

No abstract is available for this article.

Composite oxide supported Ni-based catalysts were prepared by a wet impregnation technique and applied to the methanation of carbon dioxide. The composite oxide supports were prepared by an impregnation–precipitation method using commercial γ-Al2O3 powder as a host with variation of the percentage of loading of ZrO2, TiO2, and CeO2 promoters from t...