Reforming Of Propane Research Articles

Adjusted interactions of nickel nanoparticles with cobalt-modified MgAl2O4-SiC for an enhanced catalytic stability during steam reforming of propane

Steam reforming of propane (SRP) for the stable production of hydrogen-rich reformates was investigated using the Ni-supported on the cobalt-modified SiC-embedded MgAl2O4 support (denoted as NCMAS). The adjusted interactions of the Ni nanoparticles with the cobalt-modified SiC-embedded MgAl2O4 (MgAl2O4-SiC) and its crystallite size distributions largely altered the catalytic activity and stability of NCMAS. The introductions of SiC on the NCMAS, where SiC has a higher thermal conductivity, also increased the dispersion of smaller MgAl2O4 grains with the less formations of inactive NiAl2O4 species, which resulted in the higher catalytic activity with smaller formations of unreformed light hydrocarbons. The positive roles of cobalt promoter on the MgAl2O4-SiC matrices were mainly attributed to the suppressed aggregation of nickel nanoparticles by their strong and intimate interactions with the cobalt-modified MgAl2O4. The effects of cobalt promoter at an optimal 5wt%Co in the MgAl2O4-SiC (NCMAS(5)) enhanced the oxidation-resistance of the nickel nanoparticles with less formations of inactive metal aluminates by being reversibly re-reduced under the SRP reaction conditions. These phenomena further lessen coke depositions by intimately interacting with highly dispersed oxophilic cobalt or cobalt aluminate species. The optimal NCMAS(5) was applied to derive kinetic parameters using Langmuir-Hinshelwood-Hougen-Watson (LHHW) mechanisms, and the reasonable activation energy of 73 kJ/mol and optimal operating parameters to maximize hydrogen production by SRP reaction was estimated in terms of the reaction conditions such as space velocity, feed ratio and reaction temperature.

Synergies between Ni, Co, and Mn ions in trimetallic Ni1-xCoxMnO4 catalysts for effective hydrogen production from propane steam reforming

To suppress the rapid degradation of Ni-based catalysts, Co along with Ni was used as a catalytic active species with a Mn oxide promoter that has excellent oxygen transfer ability. This study examines the optimal ratios between Ni and Co in the synthesized catalyst Ni1-xCoxMnO4 for high hydrogen production in the propane reforming reaction. The synthesized catalysts were characterized by XRD, TEM, XPS, and TPD of CO, C3H8, and H2O, and TPR of H2. In addition, the reaction mechanism of propane reforming and the behaviors of the gases adsorbed on the catalyst were investigated by NMR analysis. The results confirmed that the reduction of Ni mainly occurs before that of Co, which means that Ni acts as the main active species. In addition, gas adsorption increases over catalysts that contain both Ni and Co; the synthesized catalysts also showed improved catalytic activities. The optimum ratio of Ni:Co is 0.6:0.4, with high hydrogen evolution of >80%; complete propane conversion was obtained for the 30Ni00.6Co0.4MnO4/Al2O3 catalyst over 10 h.

Thermodynamic equilibrium analysis of combined dry and steam reforming of propane for thermochemical waste-heat recuperation

The thermochemical waste-heat recuperation is one for perspective way of increasing the energy efficiency of the fuel-consuming equipment. In this paper, the thermochemical waste-heat recuperation (TCR) by combined steam-dry propane reforming is described. To understand the influence of technological parameter such as temperature and composition of inlet gas mixture on TCR efficiency, thermodynamic equilibrium analysis of combined steam-dry propane reforming was investigated by Gibbs free energy minimization method upon a wide range of temperature (600–1200 K) and different feed compositions at atmospheric pressure. The carbon and methane formation was also calculated and shown. From a thermodynamic perspective, the TCR can be used for increasing energy efficiency at temperatures above 950 K because in this range the maximum conversion rate is reached (from 1.22 to 1.30 for the different feed composition). Approximately 10 mol of synthesis gas can be generated per mole of propane at the temperatures greater than 1000 K. Furthermore, the propane conversion rate and yield of hydrogen are increased with the addition of extra steam to the feed stock. Also, undesirable carbon formation can be eliminated by adding steam to the feed. The thermodynamic equilibrium analysis was accomplished by IVTANTHERMO which is a process simulator for thermodynamic modeling of complex chemically reacting systems and several results were checked by Aspen-HYSYS.

Kinetics of low-temperature steam reforming of propane in a methane excess on a Ni-based catalyst

Systematic studies were performed on low-temperature steam conversion or low-temperature steam reforming (LTSR) of propane in an excess of methane on a Ni-based catalyst. The LTSR of the methane–propane mixture is a two-stage process involving the irreversible steam conversion of propane into carbon dioxide and hydrogen and reversible methanation of carbon dioxide. Above ~250°C, the methanation of carbon dioxide is quasi-equilibrium. The rate of propane conversion during the LTSR of the methane–propane mixture is first-order based on propane; its activation energy is ~120 kJ/mol and is almost independent of the methane, carbon dioxide, hydrogen, and steam concentrations. This very simple macrokinetic scheme allows us to correctly describe the experimental data and predict the temperature and flow rate of the mixture at which complete conversion of propane is achieved.

Surface Reaction Kinetics of the Oxidation and Reforming of Propane over Rh/Al2O3 Catalysts

AbstractA multi‐step surface reaction mechanism for partial oxidation and steam reforming of propane over Rh/Al2O3 catalysts is presented. The mechanism is also applicable to model reactions of the subsystems H2/CO/H2O/CO2/O2/CH4. A stagnation–flow reactor with a catalytically coated disk is used to determine the surface reaction rate and spatial concentration profiles on top of the catalytic plate using a micro‐probe sampling technique. The reactor configuration facilitates one‐dimensional modeling of coupled diffusive and convective transport within the gas‐phase boundary layer coupled with detailed heterogeneous chemistry models of the zero‐dimensional surface. The reaction system is studied at varying inlet concentrations and temperatures. The established reaction kinetics are furthermore tested by simulation of autothermal reforming of propane in an annular reactor previously described by Pagani.

Oxidative reforming of propane with oxygen permeating membrane reactor using Pr2Ni0.75Cu0.25Ga0.05O4 perovskite related mixed conductor

Reforming of propane for the production of syngas can improve the utilisation of petroleum products in chemical and energy processes as it is a major constituent in refinery gas. The search for catalytic and selective membranes for the efficient conversion of natural gas with carbon higher than methane is very attractive and remains challenging. Since Pr2Ni0.75Cu0.25Ga0.05O4 possesses high mixed conductivity and oxygen permeation properties, it is extensively investigated for potential application for oxygen membrane reforming of propane in this study. The membrane is coated with La0.5Sr0.5CoO3 and Ni catalysts to achieve surface activity for oxygen dissociation and propane oxidation, respectively. The propane reforming efficiency of the membrane specimens with a 0.3mm thickness are studied as a function of temperature (800–1000°C), using N2:C3H8:O2 reactant gases with three mixing ratios of 90:7:3, 80:14:6 and 70:20:9 at flow rate of 50–375ml/min. Over 99% of propane conversion is achieved at every gas flow rate tested. The reaction products are H2, H2O, CO, CO2, CH4, C2H6, C2H4, C3H6, C4+, and coke with the highest yield of CO and H2 (37 and 29%, respectively), are obtained at 900°C using the gas flow rate between 225 and 275ml/min. The oxygen permeation rate observed at this condition is in the range of 1600–1900μmol/cm2/min. These results suggest that the utilisation of Pr2Ni0.75Cu0.25Ga0.05O4 is promising as an oxygen membrane in the reforming of propane to syngas.

Kinetics of Mild Steam Reforming of Propane in the Presence of Excess Methane over a Ni-Containing Catalyst

Regularities of the low-temperature steam conversion or mild steam reforming (MSR) of propane in the presence of excess methane over Nicontaining catalyst were thoroughly studied. MSR of the methane-propane mixture was shown to proceed through two stages including the irreversible steam conversion of methane to carbon dioxide and hydrogen and the reversible reaction of methanation of carbon dioxide. The latter reaction is quasi-equilibrium at above ≈250 °C. The first-order rate independent of the concentrations of methane, carbon dioxide and water vapor and the activation energy equal to ca. 120 kJ/mol are characteristic of the propane transformation during MSR of the methanepropane mixture. This is a rather simple macrokinetic scheme that allows the experimental data to be correctly described and temperature and mixture flow rate to be predicted for achieving the maximal propane conversion.

Microwave-activated carbon dioxide reforming of propane over Ni/TiO2 catalysts

The use of microwave activation in Ni/TiO2-catalyzed carbon dioxide reforming of propane increases the catalytic activity and significantly reduces the coke formation in comparison with conventional thermal heating. During microwave activated reaction, C2—C3 olefins were formed, apart from CO and H2, and the selectivity to olefins reached 6%. It was suggested that exposure to microwave radiation may induce local high-temperature heating of catalytically active phases and catalyst sites, which is not inherent in conventional heating. According to X-ray absorption spectroscopy (XAS = XANES + EXAFS), unlike conventional thermal heating in a hydrogen flow, on exposure to microwave radiation, the Ni2+ cations are partly reduced to Ni0.

Anodized Aluminum Oxide Supported NiO-CeO2 Catalyst for Dry Reforming of Propane

Nano-porous anodic aluminum oxide (AAO) supported Ni-Ce mixed metal oxide catalysts were prepared and tested for dry reforming of propane to produce synthesis gas. The presence of Ce efficiently suppressed the nickel particle sintering and improved the reducibility of nickel oxide supported on the AAO. The prepared NiO-CeO2/AAO catalyst was highly efficient for the dry reforming of propane (DRP) with CO2 over a temperature range of 480–580 °C. The catalyst achieved the best reforming performance of 90%–97%, and a H2/CO ratio close to 1.37 at 580 °C. The AAO supported NiO-CeO2 catalyst can be a promising catalytic system for DRP.

Thermodynamic Modeling of Propane Reforming Processes to Quantify Hydrogen and Syngas Production with and without Product Removal

Abstract The present study aims to explore the possibility of promoting hydrogen and syngas production capacity and quality by steam (SRP) and oxidative steam (OSRP) reforming of propane with and without H2 and CO2 removal. Conditions studied are temperature range of 600–1,100 K under atmospheric pressure with steam to propane feed ratio (WPR) of 1–18, oxygen to propane feed ratio (OPR) and fractional removal of H2 and CO2 (f) ranging from 0–0.99. The results indicate that SRP with 99% H2 removal produces high H2 yield of 9.93 moles close to theoretical value of 10 moles at relatively low temperature (750 K) than SRP (950 K). Approximately identical results are achieved at 950 K with 99% CO2 removal at same conditions of WPR (12), pressure (1 atm), and complete conversion of propane. Thus, SRP with H2 removal is more energy saving process. In OSRP, lower OPR, higher WPR minimize CO and CH4 production but at the expense of H2 production. However, OSPR process is the most suitable process to provide most favourable H2/CO ratio in syngas. Molar H2/CO ratio in syngas in the range of 1–3 are found at T≥1,000 K, WPR≤6 in SRP, SRP with H2 removal (f=0.4–0.99) and OSRP (OPR=0.2–2). Thermal efficiency is higher than 80% in both SRP with H2 or CO2 removal than SRP(69.39%). The thermal efficiency in OSRP is less than 69%. Hence, propane reforming process in hydrogen selective membrane reactor, provides high quality of hydrogen at relatively lower energy utilization.

In situ Raman spectroscopic analysis of the coking resistance mechanism on SrZr0.95Y0.05O3−x surface for solid oxide fuel cell anodes

While the coking resistance of Ni/yttria-stabilized zirconia (YSZ) anodes in solid oxide fuel cells (SOFCs) toward hydrocarbon fuel can be improved by adding SrZr0.95Y0.05O3−x (SZY) as a proton conductor, the exact mechanism is still unclear. In this study, the surface chemistry of SZY is investigated using in situ Raman spectroscopy to clarify the coking resistance mechanism. Upon exposure to dry propane at 500 °C, the intensity of the Raman peaks corresponding to CO3 species decreases with time, suggesting that the surface-located CO3 groups are consumed through a reaction with deposited carbon or dry reforming of propane, which reduces the tendency of coking. These consumed CO3 groups can then be regenerated through a reaction between water vapor and deposited carbon. The presence of adsorbed water on SZY, which facilitates a carbon removal reaction and the steam reforming of propane, is confirmed by thermogravimetric analysis (TGA). The reactivity of the CO3 groups and the adsorbed water on SZY thus contribute to removing deposited carbon, resulting in the improved coking resistance of Ni/YSZ-SZY anode.

Spectroscopic characterization and catalytic activity of Rh supported on CeO2-modified Al2O3 for low-temperature steam reforming of propane

The present work aims at clarifying the effects of CeO2 addition to Al2O3 support on the surface chemical characteristics and catalytic activity of supported Rh catalysts for low-temperature steam reforming of propane. Steam reforming of propane was carried out at 500°C over Rh catalysts supported on alumina modified with different CeO2 loading (0, 5, 10, 20, 50, 75, and 100wt%). The Rh catalyst supported on 20wt% CeO2-modified alumina (2Rh/20CeAl) showed the highest propane and steam conversions, followed in decreasing order by those with 10, 5, 50, 75, 0, and 100wt% CeO2. TPR results show that the interaction between ceria and rhodium improves the reducibility of both rhodium oxide and ceria. XPS analysis indicates strong ceria–alumina interaction and strong Rh-support interaction for Rh catalysts with CeO2 loading less than 20wt%. Field-Emission SEM and AES results revealed that at 20wt% CeO2 loading, ceria was dispersed as separate nano-particles with sizes of 100–200nm on the alumina surface. At high CeO2 loading (≥50wt%) ceria particles formed conglomerates covering alumina surface. The 2Rh/20CeAl catalyst showed the highest activity for propane steam reforming possibly because the high CeO2 dispersion created a large area of ceria–alumina interface which helped increase Rh dispersion, and the strong interaction between Rh and support helped enhance the reducibility of ceria and rhodium oxide. Rh loaded onto the interfacial region of ceria and alumina is considered to be most active for the 2Rh/20CeAl catalyst.

Alkane reforming on partially sulfided CeO2 (1 1 1) surfaces

Cleanup of biomass gasification effluent requires a catalyst that can reform methane and larger hydrocarbons while tolerating the presence of H2S or, ideally, that can act as a sulfur sorbent while reforming hydrocarbons. We utilize density functional theory (DFT) methods to examine the impact of oxide sulfidation on the reforming of methane and the initial steps of propane reforming, using M-doped CeO2 catalysts. On a ceria oxy-sulfide surface, surface oxygen atoms remain active for CH bond activation via hydride abstraction whereas surface sulfur atoms are significantly less active. Methyl adsorption is slightly favored at a surface sulfur site, and though subsequent dehydrogenation steps remain viable, the final steps of methane decomposition may lead to carbon buildup on the surface. However, surface sulfur sites will be less active globally for the initial rate limiting H abstraction step, and these sites can nucleate carbon buildup. Doping CeO2 with Mn accelerates CH bond activation, aids eventual CO product desorption, and may induce sulfur tolerance by motivating CHx intermediates to bind to surface O atoms rather than surface S atoms. This work represents an initial step in the development of S-tolerant oxide catalysts for hydrocarbon reforming.

Thermodynamic Equilibrium Analysis of Propane Dehydrogenation with Carbon Dioxide and Side Reactions

A thermodynamic analysis of propane dehydrogenation with carbon dioxide was performed using constrained Gibbs free energy minimization method. Different reaction networks corresponding to different catalytic systems, including non-redox and redox oxide catalysts, were simulated. The influences of CO2/C3H8 molar ratio (1–10), temperature (700–1000 K), and pressure (0.5–5 bar) on equilibrium conversion and product composition were studied. In the presence of CO2 with a molar ratio of CO2/C3H8 = 1, the temperature of dehydrogenation can be 30 K lower than that of dehydrogenation in the presence of steam (H2O/C3H8 = 1) and about 50 K lower than that of simple dehydrogenation without dilution to achieve 60% propane conversion. It was found that the occurrence of dry reforming of propane and coke-forming side reactions could strongly impact the equilibrium product composition of the multireaction system and, therefore, these reactions should be kinetically controlled. Comparison of the simulated reactant conversions with those reported in the literatures revealed that the experimental conversion levels of propane are far below the corresponding equilibrium values due to rapid catalyst deactivation by coke, implying that research efforts should be directed toward formulation of more active and selective catalysts.

Cold plasma catalytic reaction

The plasma catalytic reaction is a brand new chemical research direction. This article summarized our previous work on DeNO<italic>_x</italic> and other reactions through plasma-catalytic process. These reactions mainly include NO decomposition, CH₄-SCR, CH₄-NSR, NH₃-NSR, PM2.5 removal, VOCs removal, CO₂ decomposition, CO₂ reforming of propane. Due to the synergistic effect, these reactions exhibited high activity at ambient temperature and low temperature.

Plasma-reduced Ni/γ–Al2O3 and CeO2–Ni/γ–Al2O3 catalysts for improving dry reforming of propane

Pristine Ni/γ–Al2O3 and CeO2–Ni/γ–Al2O3 catalysts were prepared by co-impregnation technique for dry reforming of propane. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) were used to examine the structure and morphology of the catalysts before and after the reforming reactions. The excellent interaction between catalyst active phases was observed in both CeO2–Ni/γ–Al2O3 and Ni/γ–Al2O3 stabilized with polyethelene glycol (Ni/γ–Al2O3–PEG). Towards C3H8 and CO2 conversion, the CeO2–Ni/γ–Al2O3 and Ni/γ–Al2O3–PEG showed improved catalytic activity when compared to the pristine Ni/γ–Al2O3 catalyst. Interestingly, high H2 concentration was achieved with the CeO2–Ni/γ–Al2O3 and high CO concentration with the Ni/γ–Al2O3–PEG, which is due to the nanoconfinement of nickel particles within the support and favorable metal-support interaction as a result of plasma reduction. The CeO2–Ni/γ–Al2O3 catalyst exhibited better stability for anti-sintering and coke resistance, thus exhibiting high reactivity and durability in the dry reforming.

Comparative study of propane steam reforming in vanadium based catalytic membrane reactor with nickel-based catalysts

The performance of catalytic membrane reactor with Pd-coated V membrane was examined for steam reforming of propane. The long term reforming experiment confirmed the stability of the V membrane with high hydrogen selectivity and permeability. The effect of types of hydrogen permeable membranes on the performance of the catalytic membrane reactor was studied by comparing Pd-coated V, Pd–23Ag, and Pd–10Ag membranes. The types of hydrogen separation membranes (i.e. hydrogen removal rates) did not have a marked effect on the propane conversion rates, while the product compositions were largely influenced by the hydrogen removal rate. Varying metal oxide supports of Ni-catalysts resulted in significant differences in the product compositions. Further, the evaluation of various catalyst-support systems (9wt%Ni–1wt%M/CeO2, M = Co, Pt, Ag, Ru) revealed that hydrogen yield was the highest when 1wt%Ag was added to Ni/CeO2. However, it was also found that excessive secondary metal additions can have negative impact on the catalytic behaviour of parent catalysts.

Low temperature catalytic steam reforming of propane–methane mixture into methane-rich gas: Experiment and macrokinetic modeling

Steam reforming of propane–methane mixture into methane-rich gas was studied in a fixed-bed continuous-flow reactor in a temperature interval of 150–325°C under atmospheric pressure over Ni-based catalyst. It was found that the catalyst had good performance under low steam-to-carbon ratio of 0.39–0.58 and provided equilibrium product distribution at GHSV=670–3100h−1. Macrokinetic modeling of the experimental data obtained was performed in the framework of isothermal plug-flow reactor model. For the first time the two-step macro-kinetic scheme was suggested, that includes the reactions of irreversible propane steam reforming (first-order on propane): C3H8+6H2O→3CO2+10H2 with activation energy 112kJ/mole and reversible CO2 methanation (first-order on hydrogen): CO2+4H2⇄ CH4+2H2O with activation energy 50kJ/mole. It was shown that the proposed scheme describes quantitatively all the experimental results.

Catalytic propane reforming mechanism over Zr-doped CeO2(111)

Elucidation of the elementary reaction processes involved in hydrocarbon oxidation on oxide catalysts can help guide active site optimization. We use density functional theory (DFT) methods to examine the reforming of propane over the Zr-doped CeO2 (111) surface. Numerous modeling and mechanistic questions arise in modeling this multistep reaction on oxides. The surface redox and coverage state in the reaction environment impacts energetics and must be considered. Phase diagrams of Zr-doped and pure CeO2 (111) are created based upon the partial pressure of oxygen and hydrogen, demonstrating that the surface will be reduced under operating conditions. All elementary energetics along the preferential path for propane reforming were identified, and differences in path with oxygen pressure variance were identified. The reaction path varies depending on the oxygen chemical potential as this alters at which step in the mechanism the surface will re-oxidize.

Production of synthesis gas from propane using thermal water vapor plasma

In this work, an experimental plasma-chemical reactor equipped with a water vapor plasma torch was used for catalyst-free thermal plasma reforming of propane to produce a synthesis gas. Thermal arc discharge plasma (a mixture of water vapor and argon) was generated at atmospheric pressure.The influences of the H2O vapor and C3H8 flow rates on the syngas production, composition, and energy conversion efficiency as well as specific energy requirements were investigated. The best results were obtained under the experimental conditions of H2O vapor flow rate of 360 l/min, C3H8 flow rate of 47 l/min, and input plasma torch power of 63 kW. The concentrations of the products were as follows: H2 68.9%, CO 21%, CO2 5%, CH4 0.55%, and C2H2 0.9%. The C3H8 conversion ratio, H2 yield, H2 selectivity, and CO selectivity were 100%, 67%, 48.5%, 25.3%, respectively. The highest energy efficiency and the lowest specific energy requirement were 65% and 32.7 kJ/mol, respectively, and the H2/CO ratio was 3.28. The modeling of chemical processes, based on the classical thermodynamic equilibrium reactor, was also proposed. The calculated data fit quite well the experimental results.