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In a novel process, CO2 and CH4 from the off‐gases of the coke oven and blast furnace are used in homogeneous reforming of those greenhouse gases to valuable syngas, a mixture of H2 and CO. Synthetic mixtures of the off‐gases from those large apparatuses of steel industry are fed to a high‐temperature, high‐pressure flow reactor at varying temperature, pressure, residence time, and mixing ratio of coke oven gas (COG) to blast furnace gas (BFG). In this study, a maximal reduction of 78.5 % CO2 and a CH4 conversion of 95 % could be achieved at 1350 °C, 5.5 bar, and a COG/BFG ratio of 0.6. Significant carbonaceous deposits were formed but did not block the reactor tube in the operational time window allowing cyclic operation of the process. These measurements were based on prior thermodynamic analysis and kinetic predictions using an elementary‐step reaction mechanism., A new concept and proof‐of‐principle of a novel process is presented for the reduction of CO2 emissions occurring in the steel industry. The potential of using off‐gases of the coke oven and blast furnace for the dry reforming of the CH4 to valuable syngas is investigated theoretically and experimentally. A maximal reduction of 78.5 % CO2 and a CH4 conversion of 95 % was achieved at conditions relevant for the steel industry. more...

Low temperature steam reforming in combination with hydrogen selective membranes presents great potential of intensifying the classical industrial hydrogen production process via natural gas. This concept can lead to significant environmental and process benefits, such as reduced energy needs, milder material stability requirements and considerably simplified process layouts via e.g. avoiding the use of downstream WGS reactors. Ni and Rh based catalysts supported on La 2 O 3 -CeO 2 -ZrO 2 , already identified as active and stable at these conditions, are further investigated in the current work aiming at the elucidation of reaction kinetics. Temperature programmed experiments of methane conversion in steam reforming and decomposition modes in conjunction with isotopic investigations using CD 4 are carried out, showing that cleavage of a C H bond participates in the rate determine step, whereas steam derived intermediates do not. A thermodynamically consistent microkinetic model considering a comprehensive set of surface pathways is also developed. The model describes correctly experimental trends, predicting surface CH 3 dehydrogenation to be rate limiting. Estimated model parameters further help elucidate the different catalysts’ activities. The combined approach presented shows potential to accelerate catalyst and process design efforts for the promising low temperature steam reforming hydrogen production process. more...

Steam reforming of natural gas for the production of hydrogen at low operation temperature offers significant financial and environmental advantages. However, the presence of higher hydrocarbons as minor components of natural gas can significantly affect the formation of coke and thus the effectiveness of the catalyst. In this study, the effect of the presence of C2–C3 alkanes in the feedstock on the carbon accumulation during low temperature steam reforming of methane is investigated over Ni and Rh catalysts supported on lanthanum doped ceria–zirconia mixed oxide. Both catalysts showed high resistance to coke formation and especially in the case of Rh/La/CeO 2 –ZrO 2 , the carbon accumulation detected was low even after 10 h on stream in steam reforming of all mixtures of hydrocarbons tested. The presence of higher alkanes in methane increased the amount of carbon on Ni(10)CeZrLa compared to pure methane as well as the nature of the carbonaceous species. Increase in the C-number of the additive alkane had almost no influence on the total amount of carbon formed (C/H feed ratio = constant) but favored the formation of filamentous carbon. more...

One of the most promising technologies for CO 2 capture is the Calcium Looping Cycle, which is based on the reversible carbonation reaction of CaO. The main challenge for CaL technology is the deterioration of CO 2 capture capacity during multicyclic operation. In this work, the triethanolamine (TEA) was used as a complexing agent in a modified sol–gel method for the preparation of sintering resistant CaO–Ca 3 Al 2 O 6 . The sorbent showed high capture capacity (0.45 g/g sorb. or 84% carbonation conversion) which was retained after 45 cycles. Parametric study of sorption was realized by varying the carbonation and calcination conditions (temperature and CO 2 concentration). Under severe conditions of calcination temperature at 950 °C in pure CO 2 flow after 100 cycles the sorbent still retained almost 40% of the initial sorption capacity corresponding to 30% carbonation conversion. more...

Low temperature steam reforming (400-550°C) for the production of hydrogen offers significant advantages compared to the conventional process. The milder operating conditions lead to lower operation costs and cost of construction materials. Additionally, no CO shift reactor is required due to favorable temperature for the WGS reaction. In this work, we report the catalytic performance of Ni and Rh catalysts supported on La2O3-ZrO2 and La2O3-CeO2-ZrO2 for their application in a multifuel membrane reformer operating at low temperature. The performance of the catalysts is assessed in different operating conditions in methane steam reforming (GHSV, temperature, H2O/CH4ratio) as well as in reforming of model biogas. Stability tests were conducted up to 90h on stream (1bar and 7bar) and the tendency toward carbon formation was investigated. All catalysts were active in the reforming reactions at 400-550°C and the catalysts supported on La2O3-CeO2-ZrO2 showed superiority in activity and stability probably due to the presence of ceria in the support which contributes to the reforming rate and the resistance to carbonaceous deposits. Ni(10)CeZrLa exhibited remarkably stable performance with minimum amount of carbon formed after 90h (ca. 0.05wt%). TPO and TPH analysis of the carbonaceous deposits showed that the dominating type of carbon is highly reactive and can be easily removed by oxidation or hydrogenation at 500°C. This fact makes the catalyst even more promising for the proposed low temperature process, since the catalyst can be hydrogenated by using part of the H2 production stream without further heating of the reactor. © 2015 Elsevier B.V.. more...

The reaction rate of low-temperature steam reforming was studied over two Ni-based catalysts. Experimental tests were carried out for temperatures between 400 and 550 °C and pressures between 1 and 7 bar, using methane and simulated biogas (1:1 methane-carbon dioxide mixture) as carbonaceous feed. The results were analyzed with a simplified reaction rate expression. The parameters of such expression were optimized in order to provide a tool for the design of an industrial scale reactor using the catalysts considered. © 2016 Hydrogen Energy Publications LLC more...

The catalytic performance on steam reforming and carbonaceous deposits was examined over Ni/La/CeO2-ZrO2 and Rh/La/CeO2-ZrO2 catalysts, prepared via wet impregnation. The catalytic performance tests were conducted using mixtures of C2–C4 alkanes and CH4 as steam reforming feedstock for 4 h at the temperature range of 400–550 °C and for 10 h at 500 °C, with S/C = 3 and GHSV = 70,000 h−1. Analysis on the used catalysts was carried out via temperature-programmed oxidation (TPO). Both catalysts showed high activity towards the alkane feedstock achieving product distribution close to that predicted by thermodynamics with no significant deactivation during the experiments. TPO of the used catalysts after 10 h on stream showed increased carbon depositions compared to the pure methane reforming but still at very low levels, even though the concentration of the second alkane used was much higher than the real concentration in natural gas. more...

The methane steam reforming (MSR) technology is the oldest and the most vital route to convert CH4 into H2. The conventional process usually operates in a high temperature range of 973-1173 K due to the highly endothermic nature of the reforming reaction. Necessity to increase the energy efficiency leads to the development of processes operating at low temperature and of highly active and coke resistant catalysts. An active catalyst which can provide high reforming reaction rates at low temperature ( more...