Dry reforming of hydrocarbons, alcohols, and biological compounds is one of the most promising and effective avenues to increase hydrogen (H2) production. Catalytic dry reforming is used to facilitate the reforming process. The most popular catalysts for dry reforming are Ni-based catalysts. Due to their inactivation at high temperatures, these catalysts need to use metal supports, which have received special attention from researchers in recent years. Due to the existence of a wide range of metal supports and the need for accurate detection of higher H2 production, in this study, a systematic review and meta-analysis using ANNs were conducted to assess the hydrogen production by various catalysts in the dry reforming process. The Scopus, Embase, and Web of Science databases were investigated to retrieve the related articles from 1 January 2000 until 20 January 2021. Forty-seven articles containing 100 studies were included. To determine optimal models for three target factors (hydroca... [more]

Solid oxide fuel cells can operate with carbonaceous fuels, such as syngas, biogas, and methane, using either internal or external reforming, and they represent a more efficient alternative to internal combustion engines. In this work, we explore, for the first time, an alumina membrane containing straight, highly packed (461,289 cpsi), parallel channels of a few micrometers (21 µm) in diameter as a microreformer. As a model reaction to test the performance of this membrane, the dry reforming of methane was carried out using nickel metal and a composite nickel/ceria as catalysts. The samples with intact microchannels were more resistant to carbon deposition than those with a powdered sample, highlighting the deactivation mitigation effect of the microchannel structure. The coke content in the microchannel membrane was one order of magnitude lower than in the powder catalyst. Overall, this work is a proof of concept on the use of composite alumina membrane as microchannel reactors for h... [more]

Suppressing the usage of rare-earth elements is crucial for making the catalysts sustainable. Preparing CeO2 nanoparticles is a common technique to reduce CeO2 consumption, but such nanoparticles are prone to sinter or react with the supports when subjected to heat treatments. This study demonstrated that stable CeO2 nanoparticles were deposited on MgO by the simple impregnation method. When CeO2/MgO was prepared under the dry atmosphere, the CeO2 nanoparticles remained ~3 nm in diameter even after being heated at 800 °C, which is much smaller than ~5 nm of CeO2/MgO prepared under ambient air. Temperature-programmed reduction, temperature-programmed oxidation, X-ray photoelectron spectroscopy, and in situ X-ray diffraction studies showed that CeO2/MgO exhibited higher oxygen mobility when prepared under the dry atmosphere. Dry reforming reaction demonstrated that CeO2/MgO prepared under the dry atmosphere exhibited higher activity than that prepared under ambient air and pure CeO2.

Ni-based catalysts supported on alumina derived from the pseudo-boehmite prepared by the impregnation method were employed for catalytic dry reforming of methane reaction at the temperature of 550−750 °C. The effect of calcination temperature on physicochemical properties such as the Ni dispersion, reduction degree, nickel crystallite sizes, and metal−support interaction of the catalysts was investigated. The characterization results show that increasing the catalyst calcination temperature leads to the formation of nickel-alumina spinel, which enhances the metal−support interaction and increases the reduction temperature. The nickel nanoparticle size decreases and the effective dispersion increases with the increasing calcination temperature from 450 °C to 750 °C due to the formation of nickel aluminate. The catalyst calcined at 750 °C exhibits the highest CH4 and CO2 conversion owing to the small Ni0 active sites and high Ni dispersion. In a 200 h stability test in dry reforming of m... [more]

Dry reforming of CH4 was conducted over promoted Ni catalysts, supported on mesoporous gamma-alumina. The Ni catalysts were promoted by various metal oxides (CuO, ZnO, Ga2O3, or Gd2O3) and were synthesized by the incipient wetness impregnation method. The influence of the promoters on the catalyst stability, coke deposition, and H2/CO mole ratio was investigated. Stability tests were carried out for 460 min. The H2 yield was 87% over 5Ni+1Gd/Al, while the CH4 and CO2 conversions were found to decrease in the following order: 5Ni+1Gd/Al > 5Ni+1Ga/Al > 5Ni+1Zn/Al > 5Ni/Al > 5Ni+1Cu/Al. The high catalytic performance of 5Ni+1Gd/Al, 5Ni+1Ga/Al, and 5Ni+1Zn/Al was found to be closely related to their contents of NiO species, which interacted moderately and strongly with the support, whereas free NiO in 5Ni+1Cu/Al made it catalytically inactive, even than 5Ni/Al. The 5Ni+1Gd/Al catalyst showed the highest CH4 conversion of 83% with H2/CO mole ratio of ~1.0.

Dry reforming is a very interesting process for synthesis gas generation from CH 4 and CO 2 but suffers from low hydrogen yields due to the reverse water⁻gas shift reaction (WGS). For this reason, membranes are often used for hydrogen separation, which in turn leads to coke formation at the process temperatures suitable for the membranes. To avoid these problems, this work shows the possibility of using nickel self-supported membranes for hydrogen separation at a temperature of 800 ∘ C. The higher temperature effectively suppresses coke formation. The paper features the analysis of the dry reforming reaction in a nickel membrane reactor without additional catalyst. The measurement campaign targeted coke formation and conversion of the methane feedstock. The nickel approximately 50% without hydrogen separation. The hydrogen removal led to an increase in methane conversion to 60⁻90%.

In the previous study, a dynamic and two-dimensional model for a steam methane reforming process integrated with nuclear heat production was developed. It was shown that the integrated high temperature gas-cooled reactor (HTGR)/steam methane reforming (SMR) is an efficient process for applications such as hydrogen production. In this study, it is demonstrated that combining nuclear heat with the mix of steam and dry reforming process can be a promising option to achieve certain desired H2/CO ratios for Fischer-Tropsch or other downstream energy conversion processes. The model developed in the previous study is extended to the combined steam and dry reforming process. The resulting model was validated using reported experimental data at non-equilibrium and equilibrium conditions. The dynamic and steady state performance of the integrated mixed reforming of methane and nuclear heat system was studied and it was found that in addition to desired H2/CO ratios, higher methane conversion and... [more]