Combined Reforming Of Methane Research Articles

Techno-Economic and Carbon Footprint Analyses of a Coke Oven Gas Reuse Process for Methanol Production

This paper focuses on the best way to produce methanol by Coke Oven Gas (COG) conversion and by carbon dioxide capture. The COG, produced in steelworks and coking plants, is an interesting source of hydrogen that can be used to hydrogenate carbon dioxide, recovered from flue gases, into methanol. The architecture of the reuse process is developed and the different process units are compared by considering a hierarchical decomposition. Two case studies are selected, process units are modelled, and flowsheets are simulated using computer-aided design software. A factorial techno-economic analysis is performed together with a preliminary carbon balance to evaluate the economic reliability and the environmental sustainability of the proposed solutions. The production costs of methanol are equal to 228 and 268 €/ton for process configurations involving, respectively, a combined methane reforming of COG and a direct COG separation to recover hydrogen. This cost is slightly higher than the current price of methanol on the market (about 204 €/ton for a process located in the USA in 2013). Besides, the second case study shows an interesting reduction of the carbon footprint with respect to reference scenarios. The carbon dioxide capture from flue gases together with COG utilization can lead to a competitive and sustainable methanol production process depending partly on a carbon tax.

Solar-Driven Chemical Looping Methane Reforming Using ZnO Oxygen Carrier for Syngas and Zn Production in a Cavity-Type Solar Reactor

Converting sunlight into chemical fuels and metal commodities, via solar thermochemical conversion processes, is an attractive prospect for the long-term storage of renewable energy. In this study, the combined methane reforming and ZnO reduction in a single reaction for co-production of hydrogen-rich syngas and metallic Zn was demonstrated in a flexible solar thermochemical reactor prototype, driven by highly concentrated sunlight. Using solar energy as the process heat source in chemical-looping methane reforming with the ZnO/Zn oxygen carrier is a means to reduce the dependence on conventional energy resources and to reduce emissions of CO2 and other pollutants, while upgrading the calorific value of the feedstock for the production of energy-intensive and high-value chemical fuels and materials. On-sun experiments were carried out with different operating parameters including operating temperatures (800–1000 °C), inlet methane flow-rates (0.1–0.4 NL/min), and inlet ZnO feeding-rates (0.5–1.0 g/min) both in batch and continuous modes under reduced (0.15 and 0.45 bar) and atmospheric pressures (0.90 bar), thereby demonstrating solar reactor flexibility and reliability. As a result, increasing the temperature promoted net ZnO conversion at the expense of favored methane cracking reaction, which can be lowered by decreasing pressure to vacuum conditions. Diminishing total pressure improved the net ZnO conversion but favored CO2 yield due to insufficient gas residence time. Rising ZnO feeding rate under a constant over-stoichiometric CH4/ZnO molar ratio of 1.5 enhanced ZnO and methane consumption rates, which promoted Zn and syngas yields. However, an excessively high ZnO feeding rate may be detrimental, as ZnO could accumulate when the ZnO feeding rate is higher than the ZnO consumption rate. In comparison, continuous operation demonstrated greater performance regarding higher ZnO conversion (XZnO) and lower methane cracking than batch operation. High-purity metallic Zn with a well-crystallized structure and of micrometric size was produced from both batch and continuous tests under vacuum and atmospheric pressures, demonstrating suitable reactor performance for the solar thermochemical methane-driven ZnO reduction process. The produced Zn metal can be further re-oxidized with H2O or CO2 in an exothermic reaction to produce pure H2 or CO by chemical-looping.

Effect of small quantities of potassium promoter and steam on the catalytic properties of nickel catalysts in dry/combined methane reforming

Carbon dioxide and methane are two of the principal greenhouse gases. Reduction of their content in the atmosphere is currently the subject of much worldwide research. Dry and combined reforming of methane are effective methods of CO2 and CH4 utilization and production of synthesis gas (syngas) in chemical technology. Testing of catalysts that provide the desired H2/CO ratio and long operation time is one of the critical aspects of syngas production and the focus of much study. In this study, K-promoted Ni/MgAl2O4 catalysts prepared using a co-precipitation-impregnation method with different K/Ni ratios (range of 0–0.15) were examined in dry reforming of methane (DRM). The obtained catalysts were characterized using X-ray diffractometry (XRD), atomic emission spectrometry (MP-AES), Brunauer–Emmett–Teller (BET) specific surface area, BJH pore size distribution, TEM imaging, analysis of reducibility H2-TPR, infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Hammet basicity analysis, thermogravimetric analysis (TG) and elemental carbon-hydrogen-nitrogen analysis (CHN). Promotion of nickel catalysts with potassium led to changes in nickel distribution, metal-support interactions and deceleration of carbon deposition while enhancing sorption of carbon dioxide and reduction of nH2:CO to 0.5 for 0.7 K–Ni/MgAl2O4 catalyst. To obtain the required H2:CO ratio close to unity a study on the effect of steam in inlet stream was performed. It was found that maintaining inlet stream composition equal CH4:CO2:H2O = 1.0:1.0:0.1 obtained an H2:CO ratio close to unity.

Recent Progresses in the Design and Fabrication of Highly Efficient Ni-Based Catalysts With Advanced Catalytic Activity and Enhanced Anti-coke Performance Toward CO2 Reforming of Methane.

CO2 reforming of methane (CRM) can effectively convert two greenhouse gases (CO2 and CH4) into syngas (CO + H2). This process can achieve the efficient resource utilization of CO2 and CH4 and reduce greenhouse gases. Therefore, CRM has been considered as a significantly promising route to solve environmental problems caused by greenhouse effect. Ni-based catalysts have been widely investigated in CRM reactions due to their various advantages, such as high catalytic activity, low price, and abundant reserves. However, Ni-based catalysts usually suffer from rapid deactivation because of thermal sintering of metallic Ni active sites and surface coke deposition, which restricted the industrialization of Ni-based catalysts toward the CRM process. In order to address these challenges, scientists all around the world have devoted great efforts to investigating various influencing factors, such as the option of appropriate supports and promoters and the construction of strong metal-support interaction. Therefore, we carefully summarized recent development in the design and preparation of Ni-based catalysts with advanced catalytic activity and enhanced anti-coke performance toward CRM reactions in this review. Specifically, recent progresses of Ni-based catalysts with different supports, additives, preparation methods, and so on, have been summarized in detail. Furthermore, recent development of reaction mechanism studies over Ni-based catalysts was also covered by this review. Finally, it is prospected that the Ni-based catalyst supported by an ordered mesoporous framework and the combined reforming of methane will become the future development trend.

Rational design of nickel-based catalyst coupling with combined methane reforming to steadily produce syngas

Inhibiting the aggregation of Ni particles and coke deposition on supported nickel catalysts has always been an enormous challenge in methane reforming to syngas. To address the problem, in this study, a Ce-Al-O supported Ni mesoporous catalyst (Ni/Ce-Al-O-A) was designed and synthesized by using evaporation-induced self-assembly (EISA) method and citric acid auto-reduction (AR) method, respectively. The prepared Ni/Ce-Al-O-A catalyst, without further reduction, was used for combined methane dry reforming comprising CO2 dry reforming of methane (DRM) and methane partial oxidation (MPO) to effectively produce syngas. Employing citric acid auto-reduction method for catalyst preparation directly led to the formation of metallic Ni by calcining the precursor of Ni/Ce-Al-O-A in argon atmosphere, with high dispersion and small particle size (at around 4.5 nm) of metallic Ni being obtained. The Ni/Ce-Al-O-A catalyst presented high catalytic activity, better than those of reference catalyst prepared by general impregnation method and the commercial alumina supported Ni catalyst synthesized by citric acid auto-reduction method. In a 250 h lifetime test, the Ni/Ce-Al-O-A catalyst exhibited an extremely catalytic stability and anti-coking ability, and no deactivation was observed. The excellent catalytic activity of Ni/Ce-Al-O-A catalyst was mainly attributed to the Ce-incorporated Ce-Al-O that facilitated the adsorption and activation of CO2 as well as the combined methane reforming (DRM-MPO) in which the existing oxygen could effectively inhibit the coke formation.

On the economics of methanol production from natural gas

Methanol is rated among the top chemical commodities worldwide. Its production via indirect synthesis routes from natural gas is energy intensive and costly regarding the investment and operation. This study addresses the economics of methanol synthesis routes with different reforming technologies. Processes with steam reforming, autothermal reforming, and dry methane reforming are considered for medium capacities below 3000 metric tons per day. The exergetic efficiency of these processes is 34.8%, 56.9% and 39.8%, respectively.Furthermore, combined methane reforming, two-step reforming and a parallel configuration of steam – and dry methane reforming are discussed. Their exergetic efficiency is 48.6%, 57.2% and 46.3%, respectively. The processes with endothermic reforming technology inherently feature a co-production of electricity for high efficiency.The results from an economic case study are reported. Approximately 60–70% of the investment is required for the reforming unit. The fuel cost has a contribution of 50–60% in the specific product cost. Depending on the process, the payback period is 2 to 10 years. The economic uncertainties are addressed by conducting sensitivity analyses.An exergoeconomic analysis is used to calculate the levelized cost of methanol and electricity. The two-step reforming process constitutes the most attractive design from an exergoeconomic point of view, having the lowest levelized cost of methanol and electricity production among all processes.Finally, the plants are assessed by comparing the levelized cost of methanol with the range of historical methanol prices in Europe and North America. A low natural gas price makes an operation economically viable in both continents.

Combined methane reforming by carbon dioxide and steam in proton conducting solid oxide fuel cells for syngas/power co-generation

Methane and carbon dioxide mixture can be used as the fuel in a proton conducting solid oxide fuel cell (SOFC) for power/syngas co-generation and greenhouse gas reduction. However, carbon deposition and low conversion ratio are potential problems for this technology. Apart from using functional catalytic layer in the SOFC to enhance CH4 dry reforming, adding H2O into the fuel stream could facilitate the CH4 conversion and enhance the co-generation performance of the SOFC. In this work, the effects of adding H2O to the CO2CH4 fuel on the performance of a tubular proton conducting SOFC are studied numerically. Results show that the CH4 conversion is improved from 0.830 to 0.898 after adding 20% H2O to the anode. Meanwhile, the current density is increased from 2832 A m−2 to 3064 A m−2 at 0.7 V. Sensitivity studies indicate that the H2:CO ratio can be effectively controlled by the amount of H2O addition and the H2 starvation can be alleviated, especially at high current density conditions.

Sol-gel synthesis of Co-W promoted NiAl2O4 spinel nanocatalyst used in combined reforming of methane: Influence of tungsten content on catalytic activity and stability

A stable process for green fuel production by means of a combined CO2 reforming of methane and partial oxidation was evaluated during this research work. The goal was achieved by using Co-W promoters with NiO spinel on Al2O3 support. Sol-gel technique based on the privileged characterization such as homogeneous distribution was used for the synthesis of enhanced Co-W catalyst on NiAl2O4 spinel. Structural and morphological attributes of fabricated samples were investigated through XRD, FESEM, EDX, BET and FTIR techniques. Eventually, homogeneous distribution of particles, less than 50 nm, high specific surface area and homogeneous structure were observed. Catalysts stability and resistance to carbonaceous deposits in operated conditions are evaluated by TG-DTG technique. In this study, reduction of deposited coke after the reaction was achieved by raising the tungsten amount in catalyst. According to obtained results, CoNiAl2O4 promoter with 1 wt% W (CoW1/NiAl2O4) nanocatalyst has obtained higher conversion along with high H2 and CO yields. Also, CoW1/NiAl2O4 was considered as an optimum nanocatalyst for methane combined reforming by illustrating the tremendous stability at 750 °C and during the 48 h time on stream performance.

Catalytic reforming of olive mill wastewater and methane in a Pd-membrane reactor

Olive mill wastewater (OMW) is a biomass by-product of the olive oil industry. To treat this waste, reforming has been studied as a means of both producing hydrogen/syngas and reducing the pollution resulting from OMW.This study investigated a process in which OMW was added to methane and fed into a membrane reformer. The goal was to use the large water excess in OMW for reforming the methane.The results of the experiment showed that the combined reforming of methane and OMW is characterized by high hydrogen yields, with all the organic matter (the total organic carbon of both the OMW and the methane) reacting to produce hydrogen. Particularly, at 450 °C and 500 kPa with a space velocity of 0.17 mol h−1 gCAT−1 and a steam-to-carbon ratio of 16.6, hydrogen yields around 45 g per 100 g of TOC fed were measured. This corresponds to the production of 12.3 kg of ultra-pure hydrogen per ton of treated OMW. Also, it was demonstrated that adding methane to OMW does not affect the ability of the reforming process to reduce the pollution from the wastewater.Finally, the optimum operating conditions of the membrane reformer were defined by analyzing the effect of the space velocity and steam-to-carbon ratio on hydrogen production.

Combined conversion of methane into syngas on Ni/MgO-Cr2O3 catalysts

Catalysts containing 15 wt % Ni on MgO-Cr2O3 supports with different ratios of magnesium and chromium oxides were prepared. The catalysts were tested in the reactions of partial oxidation and of carbon dioxide and combined reforming of methane into syngas. The phase composition of the catalysts was studied by X-ray diffraction analysis, and the concentration of base sites on the catalyst surface was determined by temperature-programmed CO2 desorption. The 15 wt % Ni/MgO·Cr2O3 catalyst ensures the highest output of syngas in combined reforming of methane.

Syngas Production from Reforming of Methane with CO2 and O2 over LaNi1–xCoxO3 Perovskites

Abstract The LaNi1–xCoxO3 (x = 0, 0.2, 0.4, 0.6, 0.8 and 1) perovskites were prepared by the citrate sol–gel method. The prepared compounds were characterized by using XRD, BET, ICP, SEM, EDS, TEM, TPR and TGA techniques, under the condition of as-synthesized and used samples. The results showed that the highly homogeneous and pure solids with particle sizes in the range of nanometers were obtained through this synthesis method. The XRD patterns of fresh catalysts indicated the formation of well-crystallized perovskite structure with LaNiO3 and LaCoO3 as the main phases present on the solids depending on the amount of Co-substitution. TPR analysis revealed that the reduction of the solids was more difficult when increasing the degree of substitution (x). The effects of the partial substitution of Ni by Co and reaction temperatures at atmospheric pressure were investigated in the combined reforming of methane with CO2 and O2 (CRM), after reduction of the samples under hydrogen. LaNiO3 exhibited high activity and selectivity without coke formation between all of the studied perovskites. For LaNi1–xCoxO3 perovskites, it was observed a trend to decrease the catalytic activity with increasing the Co-doping level.

In situ characterization of phase transformation and reactivity of high surface area lanthanum-based Ru catalysts for the combined reforming of methane

A lanthanum oxycarbonate phase (La2O2CO3) with high surface area was prepared as support of Ru catalysts. The metal was added by wet impregnation or incorporated during the oxycarbonate synthesis. The reactivity of the lanthanum and ruthenium species was studied through in situ Raman under dry reforming of methane conditions with and without oxygen addition. When Ru was incorporated by wet impregnation, the solid showed a higher reactivity of lanthanum oxycarbonate to the formation of La2O3 in a hydrogen flow even at low temperatures while RuOx was completely reduced at 400°C. It was also found that the reduced ruthenium species could be re-oxidized by CO2 at the reaction temperature (550°C). Under the dry reforming of methane, the metallic Ru did not change its oxidation state and the formation of graphitic carbon and oxycarbonate was observed. With the addition of oxygen, the same phase transformation occurred as in the case of the dry reforming of methane. However, the re-oxidation of Ru0 species was observed through in situ Laser Raman spectroscopy and pseudo in situ XPS measurements. These measurements allowed us to advance in the understanding of the solid transformations produced during methane reforming reactions.

Effects of Fe substitutions by Ni in La–Ni–O perovskite-type oxides in reforming of methane with CO2 and O2

LaNiO3 and LaNi1−xFexO3 (x = 0.2, 0.4, 0.6, 0.8 and 1) perovskites were prepared by the citrate sol–gel method. The prepared compounds were characterized by using thermogravimetric analysis (TGA) and X-ray diffraction (XRD), temperature programmed reduction (TPR), and inductively coupled plasma (ICP) techniques. Specific surface area of the samples was measured by BET method. Morphology study of the prepared catalysts was performed using scanning and transmission electron microscopy (SEM and TEM, respectively). The XRD patterns of fresh catalysts indicated the formation of well-crystallized perovskite structure as the main phase present in the prepared samples. The results showed that the highly homogeneous and pure solids with particle sizes in the range of nanometers were obtained through this synthesis method. TPR analysis revealed that by increasing the degree of substitution (x) the reduction of the prepared samples became difficult. The effects of the partial substitution of Ni by Fe and reaction temperatures at atmospheric pressure were investigated in the combined reforming of methane with CO2 and O2 (CRM), after reduction of the samples under hydrogen. LaNiO3 exhibited high activity and selectivity without coke formation between all of the studied perovskites. Among Fe-substituted catalysts, the following order of activity was observed: LaNiO3>LaNi0.4Fe0.6O3>LaNi0.6Fe0.4O3 > LaNi0.8Fe0.2O3 > LaNi0.2Fe0.8O3 > LaFeO3.

Investigation of the catalytic performance of Ni/MgO catalysts in partial oxidation, dry reforming and combined reforming of methane

Dry reforming, partial oxidation and combined reforming of methane (combination of partial oxidation and dry reforming) to synthesis gas over nickel catalysts supported on nanocrystalline magnesium oxide with various nickel loadings have been studied. Among the catalysts evaluated, catalyst with 15wt.% nickel content revealed the most active catalytic performance toward dry reforming, partial oxidation and combined reforming reactions. In addition, catalyst with 5wt.% nickel loading was employed in long term stability test and has shown stable catalytic performance up to 50h time on stream without any decrease in methane conversion in these three processes.

Structured Perovskite-Based Oxides: Use in the Combined Methane Reforming

The behavior of metallic structured perovskite-based catalysts was evaluated in the combined methane reforming reaction with CO2-O2. The reaction conditions were established by varying the reaction temperature and reactor input composition in the range of 650 to 850℃ and CH4/CO2 ratio 1 to 5, respectively. The results of the catalytic tests at 750℃ showed a positive effect of the metallic structure, producing higher conversions and H2/CO ratios in the products compare to that obtained with the powder catalyst.

Combined reforming of methane over supported Ni catalysts

Various supported Ni catalysts have been applied for combined steam and carbon dioxide reforming of methane to produce synthesis gas (H2/CO = 2). Highly active and stable nano-sized Ni/Mgo–Al2O3 catalyst has been successfully developed for the target reaction. The high activity and stability is due to beneficial effects of MgO such as enhanced steam adsorption, basic property, nano-sized NiO crystallite size and strong interaction between Ni and support.

Combined methane reforming in presence of CO 2 and O 2 over LaFe 1− xCo xO 3 mixed-oxide perovskites as catalysts precursors

The paper deals with the effect of modification with cobalt of a series of LaFe 1− x Co x O 3 mixed-oxide perovskites as catalyst precursors in the combined reforming of methane with CO 2 and O 2 for the production of syngas. The perovskite type oxides were synthesized by fine chemical using the citrate sol–gel method and characterized by techniques such as FT-IR, BET surface area, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), TPR and inductively coupled plasma emission spectroscopy (ICP), under the condition of as-synthesized, reduced and used samples. The results showed that through this synthesis it is possible to obtain highly crystalline, homogeneous and pure solids, with well-defined structures. After reduction, the stabilization by the presence of iron of highly dispersed Co metallic particles from the cation on position B over the corresponding oxides was evidenced, decreasing deactivation by avoiding the sintering of metals and coke formation on the surface of the catalysts. The existence of strong Fe–Co interaction in the LaFe 1− x Co x O 3 with x = 0.4–0.6 produces a synergetic effect improving methane conversion and H 2 production.

Partial oxidation and combined reforming of methane on Ce-promoted catalysts

Pt/ZrO 2 and Pt/Ce 0.14Zr 0.86O 2 catalysts containing 0.5 and 1.5 wt.% Pt were studied in order to evaluate the effect of the support reducibility and metal dispersion on the catalyst stability for the partial oxidation and the combined partial oxidation and CO 2 reforming of methane. The Pt/Ce 0.14Zr 0.86O 2 catalysts proved to be more active, stable and selective than Pt/ZrO 2 catalysts during the partial oxidation reaction. No increase in deactivation was observed when the CH 4:O 2 feed ratio was increased from 2:1 to 4:1. In addition, no water formation was observed at the high CH 4:O 2 ratios. The activity of the catalyst is dependent upon both the dispersion and the ability of the catalyst to resist carbon deposition. The addition of CO 2 resulted in a decrease in the methane conversion and a decrease in the H 2/CO ratio for the Ce 0.14Zr 0.86O 2 and ZrO 2 supported catalysts. Small increases in the temperature of the bed have been recorded during the partial oxidation reaction. However, within a few minutes the temperature stabilizes below the furnace temperature providing indirect evidence for the combined combustion and reforming mechanisms previously proposed. The 1.5 wt.% Pt/CeZrO 2 catalyst shows promise for the autothermal reforming reaction based on the stability during transient operation.