Slip casting is a significant method and it is widely used in ceramic manufacturing. In order to investigate the influence of water processing in slurry fabrication on microstructure and oxygen permeation of Ba1.0Co0.7Fe0.2Nb0.1O3−δ (BCFN) membrane, disk-shaped membranes are made from powders with/without water processing and these membranes are checked by XRD, SEM and oxygen permeation measurement. We find barium of material dissolves into water during slurry fabrication through ICP-OES method and the A-site stoichiometric ratio is 0.986 because of the water processing, and the oxygen permeation flux of water-treated membrane is 25.2% lower than that of original membrane after sintered at 1110 °C. With the increase of sintering temperature, the oxygen permeation of water-treated membrane almost recovers and is only 7% lower than the original membrane while sintered at 1150 °C. A composition segregation and homogenization mechanism is proposed through microstructure and properties analysis.Highlights► Nonuniformity of BCFN-powder due to barium dissolution in water. ► High sintering temperature increases oxygen permeation of water-treated membranes. ► Grain size of water-treated membrane depends sharply on sintering temperature. ► A phase layer with barium-deficiency at surface of powders after water processing.

A series of Ni/MgxAl catalysts with different Mg/Al molar ratios were prepared by impregnating Mg–Al mixed oxides with nickel nitrate aqueous solution and used for the pre-reforming of LPG in the temperature range of 400–500 °C. XRD and H2-TPR results showed that the Ni/MgxAl catalysts calcined at 800 °C mainly consisted of γ-Al2O3, Mg(Ni)Al2O4 and Mg(Ni)O phases varying with Mg/Al molar ratio without free NiO species observed. The effects of Mg/Al molar ratio, S/C molar ratio and reaction temperature on the catalytic behavior of the Ni/MgxAl catalysts were investigated in detail. The results revealed that the catalyst with Mg/Al molar ratio of 1.25 had the highest catalytic activity and stability. The increase in S/C molar ratio promoted both the steam reforming of LPG and the methanation of carbon oxides and hydrogen. The stability tests of 15%Ni/Mg1.25Al catalyst showed that the catalyst was stable for the pre-reforming of LPG, and the stability decreased with elevating the reaction temperature due to more coke deposition.

The perovskite-type oxygen separation membranes BaCo0.7Fe0.2Nb0.1O3−δ (BCFN) combined with Ce0.8Re0.2O2−δ (Re = Sm, Gd) surface modification layers was investigated for hydrogen production by partial oxidation reforming of coke oven gas (COG). The Ce0.8Re0.2O2−δ materials improve the oxygen permeation flux of the BCFN membrane by 8–31% under the COG atmosphere at 875 °C. The high oxygen permeation flux achieved using the Ce0.8Gd0.2O2−δ surface-coating layer in this work is quite encouraging with a maximum value reaching 21.9 ml min−1 cm−2 at 900 °C. Characterization of the membrane surfaces by SEM and XRD after 100 h long life test show that the Ce0.8Gd0.2O2−δ surface-coating layer on the permeation side can dramatically withstand corrosion of the hash strong reductive working conditions, which will be promising surface modification material in the catalytic partial oxidation reforming of COG using oxygen-permeable ceramics.

A high oxygen permeability and sufficient chemical and mechanical stability mixed ion and electron conductivity membrane to withstand the hash strong oxidation and reduction working conditions is significant for the membrane reactor to commercial-scale plant. In this paper, a disk-shaped Ba1.0Co0.7Fe0.2Nb0.1O3−δ membrane was applied to a membrane reactor for the partial oxidation of methane in coke oven gas (COG) to syngas. The reaction was carried out using NiO/MgO solid solution catalyst by feeding COG. The reforming process was performed successfully; 95% CH4 conversion, 80% H2 selectivity, 106% CO selectivity and 16.3 ml cm−2 min−1 oxygen permeation flux were achieved at 1148 K. The reaction has been steadily carried out for more than 100 h. The NiO/MgO catalyst used in the membrane reactor exhibited good catalytic activity and resistance to coking in the COG atmosphere. Characterization of the membrane surface by SEM and XRD after long life test showed that both the surface exposed to the air side and reaction side still preserved the Perovskite structure which is implied that the practical application of this membrane as membrane reactor for partial oxidation of COG is promising.

The steam reforming of coke oven gas (COG) for hydrogen production was investigated over the NiO/MgO solid solution catalysts reduced at high temperatures. It was found that the NiO/MgO catalyst possessed good catalytic activity, and the conversions of CH4 and CO2 were greatly affected by the reaction temperature and steam/carbon (S/C) mole ratio. During the tested period of 100 h under a low S/C ratio of 1.0 at 875 °C, the conversions of CH4 and CO2 kept constant values around 97.6 and 44.3%, respectively, and the hydrogen volume content was enhanced from 58.2% in the original COG to 77.7% by 1.5 times. The catalyst characterization results of X-ray diffraction (XRD), transmission electron microscopy (TEM), and thermogravimetry (TG) after the reaction showed that the Ni nanoparticle sizes had a slight increase and the amount of the coke deposition was ca. 1%. These results showed that the NiO/MgO catalyst was efficient and stable for the steam reforming of COG to amplify hydrogen in COG. This research will be of importance in hydrogen production from COG.

Catalysts of Ni/Mg(Al)O promoted with lanthanum and cerium were tested in a BaCo0.7Fe0.2Nb0.1O3-δ (BCFNO) membrane reactor by catalytic partial oxidation of simulated hot coke oven gas (COG) with toluene as a model tar compound under atmospheric pressure. Analysis of the catalysts suggested that the hydrotalcite precursor after thermal treatment lead to a good dispersion of nickel forming the solid solution NiO−MgO and spinel (Ni,Mg)Al2O4. The promoted catalysts had higher oxygen permeation flux, better catalytic activity, and better resistance to carbon formation, which will be promising catalysts in the catalytic partial oxidation reforming of hot COG.

Hydrogen production from simulated hot coke oven gas (HCOG) was investigated in a BaCo0.7Fe0.2Nb0.1O3−δ (BCFNO) membrane reactor combined with a Ni/Mg(Al)O catalyst by the partial oxidation with toluene as a model tar compound under atmospheric pressure. The reaction results indicated that toluene was completely converted to H2 and CO in the catalytic reforming of the simulated HCOG in the temperature range from 825 to 875 °C. Both thermodynamically predicated values and experimental data showed that the selective oxidation of toluene took precedence over that of CH4 in the reforming reaction. At optimized reaction conditions, the dense oxygen-permeable membrane has an oxygen permeation flux around 12.3 mL cm−2 min−1, and a CH4 conversion of 86%, a CO2 conversion of 99%, a H2 yield of 88%, and a CO yield of 87% have been achieved. When the toluene and methane were reformed, the amount of H2 in the reaction effluent gas was about 2 times more than that of original H2 in simulated HCOG. The results reveal that it is feasible for hydrogen production from HCOG by reforming hydrocarbon compounds in a ceramic oxygen-permeable membrane reactor.

CeO2-, La2O3-, and ZrO2-promoted Ni/Mg(Al)O catalysts synthesized by hydrotalcite-type precursors have been investigated with respect to catalytic activity and carbon formation in the hydrogenation and steam reforming of toluene as a model tar compound. X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) specific surface area and H2-temperature programmed reduction (TPR) were used to observe the characteristics of the prepared catalysts. The carbon formation and its amount on the used catalysts were examined by transmission electron microscope (TEM), scanning electron microscope (SEM) and thermogravimetric (TG). The trend of catalytic activity as derived from the experimental results followed the order: Ni-Ce>Ni-Las>Ni-Zr>Ni. The catalyst modified with CeO2 exhibited the highest catalytic performance and had good carbon resistance in the hydrogenation and steam reforming of toluene. A toluene conversion of 96.8%, a CH4 yield of 45.2% and a CO yield of 50.4% have been achieved. The addition of promoters led to better dispersion of nickel species and higher interaction nickel-support, which were favorable for increasing the catalytic activity and effectively preventing carbon formation.

Hydrogen production by catalytic reforming of simulated hot coke oven gas (HCOG) with toluene as a model tar compound was investigated in a fixed bed reactor over Ni/Mg(Al)O catalysts. The catalysts were prepared by a homogeneous precipitation method using urea hydrolysis and characterized by ICP, BET, XRD, TPR, TEM and TG. XRD showed that the hydrotalcite type precursor after calcination formed (Ni, Mg)Al2O4 spinel and Ni-Mg-O solid solution structure. TPR results suggested that the increase in Ni/Mg molar ratio gave rise to the decrease in the reduction temperature of Ni2+ to Ni0 on Ni/Mg(Al)O catalysts. The reaction results indicated that toluene and CH4 could completely be converted to H2 and CO in the catalytic reforming of the simulated HCOG under atmospheric pressure and the amount of H2 in the reaction effluent gas was about 4 times more than that in original HCOG. The catalysts with lower Ni/Mg molar ratio showed better catalytic activity and resistance to coking, which may become promising catalysts in the catalytic reforming of HCOG.

Hydrogen amplification from simulated hot coke oven gas (HCOG) was investigated in a BaCo0.7Fe0.2Nb0.1O3-δ (BCFNO) membrane reactor combined with a Ru-Ni/Mg(Al)O catalyst by the partial oxidation of hydrocarbon compounds under atmospheric pressure. Under optimized reaction conditions, the dense oxygen permeable membrane had an oxygen permeation flux around 13.3 ml/(cm2·min). By reforming of the toluene and methane, the amount of H2 in the reaction effluent gas was about 2 times more than that of original H2 in simulated HCOG. The Ru-Ni/Mg(Al)O catalyst used in the membrane reactor possessed good catalytic activity and resistance to coking. After the activity test, a small amount of whisker carbon was observed on the used catalyst, and most of them could be removed in the hydrogen-rich atmosphere, implying that the carbon deposition formed on the catalyst might be a reversible process.

The performance of LiNi/-Al2O3 catalysts modified by rare earth metal oxide (La2O3 or CeO2) packed on BCFNO membrane reactor was discussed for the partial oxidation of methane (POM) in coke oven gas (COG) at 875 °C. The NiO/γ-Al2O3 catalysts with different amounts of La2O3 and CeO2 were prepared with the same preparation method and under the same condition in order to compare the reaction performance (oxygen permeation, CH4 conversion, H2 and CO selectivity) on the membrane reactor. The results show that the oxygen permeation flux increased significantly with LiNiREOx/γ-Al2O3 (RE = La or Ce) catalysts by adding the element of rare earth especially the Ce during the POM in COG. Such as, the Li15wt%CeO29wt%NiO/-Al2O3 catalyst with an oxygen permeation flux of 24.71 ml·cm−2·min−1 and a high CH4 conversion was obtained in 875 °C. The resulted high oxygen permeation flux may be due to the added Ce that inhibited the strong interaction between Ni and Al2O3 to form the NiAl2O4 phase. In addition, the introduction of Ce leads up to an important property of storing and releasing oxygen.