Reforming Of Propane Research Articles

Numerical Simulation of Methane and Propane Reforming Over a Porous Rh/Al2O3 Catalyst in Stagnation-Flows: Impact of Internal and External Mass Transfer Limitations on Species Profiles

Hydrogen production by catalytic partial oxidation and steam reforming of methane and propane towards synthesis gas are numerically investigated in stagnation-flow over a disc coated with a porous Rh/Al2O3 layer. A one-dimensional flow field is coupled with three models for internal diffusion and with a 62-step surface reaction mechanism. Numerical simulations are conducted with the recently developed computer code DETCHEMSTAG. Dusty-Gas model, a reaction-diffusion model and a simple effectiveness factor model, are alternatively used in simulations to study the internal mass transfer inside the 100 µm thick washcoat layer. Numerically predicted species profiles in the external boundary layer agree well with the recently published experimental data. All three models for internal diffusion exhibit strong species concentration gradients in the catalyst layer. In partial oxidation conditions, a thin total oxidation zone occurs close to the gas-washcoat interface, followed by a zone of steam and dry reforming of methane. Increasing the reactor pressure and decreasing the inlet flow velocity increases/decreases the external/internal mass transfer limitations. The comparison of reaction-diffusion and Dusty-Gas model results reveal the insignificance of convective flow on species transport inside the washcoat. Simulations, which additionally solve a heat transport equation, do not show any temperature gradients inside the washcoat.

Effects of Pt precursors on Pt/CeO2 to water-gas shift (WGS) reaction activity with Langmuir-Hinshelwood model-based kinetics

The crystallite size effects of Pt nanoparticles on the CeO2 (Pt/CeO2) prepared with four different Pt precursors were investigated in terms of their thermal stability and catalytic activity for a water-gas shift (WGS) reaction using the compositions of reformates after a typical steam reforming of propane. The Pt/CeO2 prepared with a diamine dinitroplatinum (Pt(NO2)2(NH3)3) precursor, which forms the cationic Pt(NH3)22+ species on the negatively-charged CeO2 surfaces, revealed a superior catalytic activity and thermal stability by forming the partially oxidized smaller Pt nanoparticles decorated with metallic Pt surfaces as well as by forming the strongly interacted PtOx-CeO2 interfaces. The stable preservation of the pristine smaller Pt nanoparticles with small aggregations even under the hysteresis test from 250 to 400 °C was mainly attributed to the strong metal-support interactions. The optimized Pt/CeO2 was further studied to obtain kinetic equations derived by Langmuir-Hinshelwood (LH) model, and the optimal operating conditions of WGS reaction were found to be ~280 °C and H2O/CO molar ratio of 9 with the activation energy of ~78.4 kJ/mol.

Efficient hydrogen production by low-temperature steam reforming of propane using catalysts with very small amounts of Pt loaded on NiMn2O4 particles

The purpose of the present work is to unveil the effect of very small amounts of Pt loaded onto a NiMn2O4 spinel catalyst on the chemical characteristics and catalytic activity for low-temperature steam reforming (LTSR) of propane. In the H2-TPR curves of the Pt-loaded catalysts, the reduction corresponding to Pt2+ → Pt0 occurred largely at approximately 200–350 °C. It is due to the high accumulation of hydrogen on the PtNi alloy. X-ray photoelectron spectroscopy measurements proved that the PtNi component acted as the active species. The catalysts with Pt loaded on 40NiMn2O4/60γ-Al2O3 show higher propane conversion due to the larger metal interface area created between Pt, Ni, and MnO. In particular, the 40Pt0.025NiMn2O4/60γ-Al2O3 catalyst maintained a very low amount of carbon deposition, a stable propane conversion of 100% and a hydrogen production capacity of 60% at 450 °C, even after 100 h of LTSR.

Controlling Selectivity and Stability in the Hydrocarbon Wet-Reforming Reaction Using Well-Defined Ni + Ga Intermetallic Compound Catalysts

In this study, we present the use of compositionally and structurally well-defined, oxide-supported nanoparticle Ni + Ga intermetallic compound (IMC) catalysts in the wet reforming of propane. The definition of the IMC catalysts allowed for more direct connections to be made between catalyst bulk and surface compositions and catalyst performance in wet reforming. We show that Ni + Ga catalysts exhibit comparable or better rates of reaction on a per-site basis and improved stability in comparison to other leading formulations. We also demonstrate excellent control over product selectivity as a function of Ni + Ga IMC bulk and surface compositions with nearly ideal selectivity toward CO2/H2 or CO/H2 achieved. Selectivity toward the production of smaller hydrocarbons could also be suppressed significantly due to uniquely limited rehydrogenation kinetics of the Ni + Ga IMCs. Our studies also shed light on the stability of Ni + Ga IMCs under reaction conditions and how high conversion in reactions that involve many strongly bound reaction intermediates can lead to IMC phase relaxation to the most stable phase with concomitant surface composition and catalytic performance changes. Correlations between surface chemistry and catalyst performance were afforded by both the well-defined nature of the IMCs and computational surface science studies.

How to choose endothermic process for thermochemical waste-heat recuperation?

The thermochemical waste-heat recuperation (TCR) systems by steam reforming of various hydrocarbon fuels are considered. A method for determining the TCR systems efficiency is proposed. The methodology is based on the determination of the heat recuperation rate and heat transformation coefficient. TCR due to steam reforming of methanol, ethanol, glycerol, propane, and methane was analyzed. To obtain the initial data for energy analysis of TCR systems, the thermodynamic analysis was performed. With the help of Aspen HYSYS was determined the synthesis gas composition and reaction enthalpy for all investigated variants. The investigation was performed for a wide temperature range from 400 to 1200 K, for the steam-to-fuel ratio of 1, and pressures of 1 bar. It was established that TCR due to the steam reforming of ethanol, glycerol, and propane in the temperature range above 800 K, it is possible to achieve complete recuperation of the exhaust after the furnace. As a results of investigation, the practical recommendations were given for choosing endothermic reaction for the thermochemical waste-heat recuperation systems: in the temperature range up to 600 K for TCR it is necessary to choose a methanol steam reforming reaction; in the temperature range from 600 to 1000 K - the reaction of steam reforming of ethanol and glycerol; in the temperature range above 1000 K - the reaction of steam reforming propane and methane.

Synergy Effects of Cobalt Oxides on Ni/Co-Embedded Al2O3 for Hydrogen-Rich Syngas Production by Steam Reforming of Propane

The synergetic effects of Co oxides on the Ni/CoAl (NCA) catalysts were observed at an optimal molar ratio of Al/Co = 2 (NCA(2)) due to the partial formations of thermally stable spinel CoAl2O4 phases for the steam reforming of propane (SRP). The optimal content of the spinel CoAl2O4 phases on the NCA(2) was responsible for the formation of the relatively active oxophilic metallic Co nanoparticles with a smaller amount of less active NiAl2O4 on the surfaces by preserving the relative amount of metallic Co of 68% and 52% in the reduced and used catalysts, which enhanced the catalytic activity and stability with the largest specific rate of 1.37 C3H8/(Ni + Co)h−1 among the tested NCA catalysts. The larger or smaller amounts of Co metal on the less active NCA mainly caused the preferential formation of larger aggregated Ni nanoparticles ~16 nm in size due to their weaker interactions, or induced the smaller formations of active metal phases by selectively forming the spinel NiAl2O4 phases with ~60% in the NCA(4), resulting in a fast deactivation.

Hydrogen production via steam reforming of propane over supported metal catalysts

Catalytic performance of supported metal catalysts for propane steam reforming reaction was investigated with respect to the nature, loading and mean crystallite size of metal as well as with respect to the nature of the support. Activity was found to be improved in the order Re<Ni<Pt<Ru<Ir<Rh, with Rh being one order of magnitude more active than Re. Increasing metal loading results in a significant shift of the C3Η8 conversion curve toward lower temperatures. In the case of Ru/Al2O3 and Ru/TiO2 catalysts, turnover frequency (TOF) of C3H8 conversion increases by four orders of magnitude and by a factor of 5 with increasing Ru crystallite size in the ranges of 1.3–13.6 nm and 0.9–4.2 nm, respectively. Different results were obtained for Rh/Al2O3 catalysts, where TOF seems not to be appreciably affected by varying Rh particle size between 1.4 and 5.1 nm. The support nature affects significantly catalytic activity of Rh, which increases following the order CeO2<SiO2<Al2O3<ZrO2<TiO2<YSZ.

Integrated coal pyrolysis with steam reforming of propane to improve tar yield

An integrated process of coal pyrolysis with steam reforming of propane (CP-SRP) to improve tar yield was studied using Ni/Al2O3 as reforming catalyst. Comparing with coal pyrolysis under N2 atmosphere (CP-N2), the CP-SRP and the integrated coal pyrolysis with steam reforming of methane (CP-SRM) or methane with a few propane (CP-SRMP) show higher tar yield. Tar yield reaches its maximum at 600 °C in CP-SRP, which is 1.17, 1.14, and 1.11 times that in CP-N2, CP-SRMP and CP-SRM, respectively. Simulated distillation and GC–MS were used to characterize the fraction distributions and compositions of tar, which indicated the tar from CP-SRP has higher light oil, phenols and naphthalenes content than that from CP-N2. Isotopic tracer agents like C3D8 and D2O were used to study the tar formation mechanism in CP-SRP. The radicals like D, CD3 generated by activated C3D8 and D2O in SRP combine with radicals formed from coal pyrolysis to improve tar yield and change the product distribution.

Influence of the Catalyst Particle Size on the Aqueous Phase Reforming of n-Butanol Over Rh/ZrO2.

Butanol is a by-product obtained from biomass that can be valorized through aqueous phase reforming. Rh/ZrO2 catalysts were prepared and characterized, varying the size of the support particles. The results showed a relatively mild effect of internal mass transport on butanol conversion. However, the influence of internal transport limitations on the product distribution was much stronger, promoting consecutive reactions, i.e., dehydrogenation, hydrogenolysis, and reforming of propane and ethane. Hydrogen consuming reactions, i.e., hydrogenolysis, were more strongly enhanced than hydrogen producing reactions due to internal concentration gradients. Large support particles deactivated faster, attributed to high concentrations of butyraldehyde inside the catalyst particles, enhancing deposit formation via aldol condensation reactions. Consequently, also the local butyric acid concentration was high, decreasing the local pH, enhancing Rh leaching. The influence of internal transfer limitation on product distribution and stability is discussed based on a reaction scheme with three main stages, i.e., (1) formation of liquid intermediates via dehydrogenation, (2) formation of gas via decarbonylation/decarboxylation reactions, and (3) hydrocarbon hydrogenolysis/reforming/dehydrogenation.

Propane steam reforming over promoted Ni–Ce/MgAl2O4 catalysts: Effects of Ce promoter on the catalyst performance using developed CCD model

In this work, the effects of Ni metal phase and Ce promoter over xNi-yCe/MgAl2O4 (x = 2.75, 5, 10, 15, 17.07 wt% and y = 0.17, 1, 3, 5, 5.83 wt%) catalysts were systematically studied in steam reforming of propane (SRP). Catalysts were synthesized by co-impregnation of Ni(NO3)2.6H2O and Ce(NO3)2.9H2O on the co-precipitated support with MgO/Al2O3 stoichiometric ratio of 1.0. Based on the catalyst structure, the XRD, N2 adsorption-desorption, H2-TPR, SEM, EDX mapping, TG-DTA, and Raman spectroscopy were used to explain the catalyst performance. The C3H8 conversion, H2 yield, and stability were evaluated at T = 600 °C, GHSV = 30000 ml/(h.grcat), H2O/C3H8 = 3, and P = 1 atm during 420 (min) reaction time. Loading Ni on the MgAl2O4 support resulted in beneficial C3H8 conversion and H2 yield, however, it worsens the catalyst performance in long term reaction as a result of more coke formation. The good performance of Ce-promoted catalysts might be attributed to small crystallite size, high specific surface area, and low carbon deposition on the catalyst surface. Moreover, as suggested by TPR and XRD, the interaction between Ce and Ni may prevent Ni from distributing inside the support structure (solid solution), avoiding the catalyst from later coking. The optimum catalyst of 11.85Ni-3.55Ce was achieved using the central composite design (CCD) method, considering the maximum C3H8 conversion and H2 yield as well as minimum deactivation. The C3H8 conversion, H2 yield, and deactivation were experimentally lead to 96%, 63%, and 1%, respectively, and were in good agreement with predicted data by developed CCD method.

Effects of Ce, La, Cu, and Fe promoters on Ni/MgAl2O4 catalysts in steam reforming of propane

The effects of nickel loading and type of promoter on the performance of xNi/MgAl2O4 (x=5, 10, and 15 wt%) and 10Ni-3M/MgAl2O4 (M=Ce, La, Cu, Fe) catalysts, respectively, in steam reforming of propane (SRP) were investigated. The catalyst support (MgAl2O4) was synthesized by co-precipitation method with a MgO/Al2O3 mole ratio of 1.0. The catalysts were then prepared by impregnation of nitrates of nickel and promoters on the support. The catalysts were characterized by the XRD, nitrogen adsorption-desorption, TPR, SEM, EDX mapping, and TGA, and the SRP performance was evaluated in a fixed bed reactor at reaction temperature=500–700 °C, pressure=1 atm, C3H8:N2: steam feed ratio=1:1:3, and GHSV=30,000 ml/(h·gcat) during 420 min time on stream. The results indicated that C3H8 conversion, H2 yield, and catalyst stability varied significantly with nickel loading and type of promoter in the catalyst. The 10Ni/MgAl2O4 catalyst showed highest C3H8 conversion (78%), H2 yield (49%), and stability (96%) as compared to the other unpromoted catalysts due to optimum nickel loading and less carbon deposition. Moreover, cerium promoter remarkably enhanced the performance of 10Ni-3Ce/MgAl2O4 catalyst (C3H8 conversion=93%, H2 yield=60%, and stability= 100%) via more coke gasification in the course of SRP reaction.

The effects of bimetallic interactions for CO2‐assisted oxidative dehydrogenation and dry reforming of propane

AbstractThe catalytic reduction of CO2 by propane may occur via dry reforming to produce syngas (CO + H2) or oxidative dehydrogenation to yield propylene. Utilizing propane and CO2 as coreactants presents several advantages over conventional methane dry reforming or direct propane dehydrogenation, including lower operating temperatures and less coke formation. Thus, it is of great interest to identify catalytic systems that can either effectively break the CC bond to generate syngas or selectively break CH bonds to produce propylene. In this study, several precious and nonprecious bimetallic catalysts supported on reducible CeO2 were investigated using flow reactor studies at 823 K to identify selective catalysts for CO2‐assisted reforming and dehydrogenation of propane.

Effects of simultaneous calcination and reduction on performance of promoted Ni/SiO2 catalyst in steam reforming of propane

The effects of distinct and simultaneous calcination and reduction (DCR & SCR) processes were determined over 10Ni/SiO2 catalyst. The results showed that the C3H8 conversion and H2 yield increased from 69% to 51% for DCR to 91% and 64% for SCR catalyst. Calcination before reduction seemed to be resulting in the construction of larger Ni particles and it may be due to partial phyllosilicates decomposition. According to the initial tests, to elevate the C3H8 conversion and H2 yield, the effects of promoters such as La, Ce, K, and Sr were examined on the catalyst performance. Activity test illustrated that K and Sr declined the propane conversion and H2 yield, however, Ce and La increased them. Synthesized catalysts were characterized using XRD, BET, H2-TPR, SEM, and TGA/DTA to determine the structural properties. Consistent with BET and XRD analysis, K and Sr had the low surface area and large Ni crystallite size, contributing to coke deposition on the catalyst surface. Among the promoted samples, La-containing catalyst showed good activity and then, in the rest of this work, 10Ni-yLa/SiO2 (y = 2, 5, 8 wt%) catalysts were examined. The results showed that 10Ni2La/SiO2 catalyst improved the particle dispersion and decreased the particle size so that specific surface area and porous volume were maximized and minimized, respectively. 10Ni2La/SiO2 catalyst at GHSV of 45000 (ml/h.gcat), the temperature of 640C, and S/C = 3 in 420 min time-on-stream showed the best performance, that is C3H8 conversion of 95% and H2 yield of 69% in propane steam reforming (PSR).

Dry Reforming of Propane over γ-Al2O3 and Nickel Foam Supported Novel SrNiO3 Perovskite Catalyst

The SrNiO3 perovskite catalyst was synthesized by the citrate sol-gel method and supported on γ-Al2O3 and Nickel foam, which was used to produce syngas (CO and H2) via dry reforming of propane (DRP). Several techniques characterized the physicochemical properties of the fresh and spent perovskite catalyst. The X-ray diffractograms (XRD) characterization confirmed the formation of the perovskite compound. Before the catalytic activity test, SrNiO3 perovskite catalyst was reduced in the H2 atmosphere. Results indicated that the H2 reduction slightly increased the activity of the SrNiO3 perovskite catalyst. The catalytic activity was examined for the CO2/C3H8 ratio of 3 and reaction temperatures in the range of 550 °C–700 °C. The results from the catalytic study achieved 88% conversion of C3H8 and 66% conversion of CO2 with SrNiO3/NiF at 700 °C. Also, syngas with a maximum concentration of 21 vol.% of CO and 29 vol.% of H2 was produced from the DRP. The strong basicity of SrNiO3 perovskite enhanced the CO selectivity, resulting in minimal carbon formation. Post reaction catalyst characterization showed the presence of carbon deposition which could have originated from propane decomposition.

Effect of the Light Alkane Content of Natural Gas on the Production of Hydrogen and Coke During the Dry Reform

Dry reforming of ethane and propane were carried out with a nickel catalyst (3.92% by weight/γ-Al2O3) to characterize the effects of fed light alkanes on the reforming process of natural gas. Conversions of individual alkanes, representing 74.7% for ethane and 96.0% for propane at 1073 K, promoted hydrogen yields of 43.6% and 66.0%, respectively. The conversion (81%) of a natural gas promoted a 95% hydrogen yield, where about 20% had been obtained from the light alkanes. The reaction steps from alkane dry reforming where hydrogen was produced (alkane cracking) provided carbon formation with a yield of 23%. A kinetics evaluation, based on experimental evidence that indicated two different sets of reaction steps for both ethane and propane processes, enabled the identification of the specific reaction rates of the cracking steps for each alkane. Reaction steps in the reforming process were considered as competitive reactions and the specific cracking reaction rates of both light alkanes were used to quantify the kinetic selectivities of hydrogen, calculated as 95.42% for ethane and 76.99% for propane.

Oxy-dry reforming of propane over Ce-promoted Co\u2013Ni/Al2O3 catalyst

This paper reports the production of syngas from two types of O2-assisted dry reforming of propane, namely oxidative (O2-dosed) dry reforming (ODR) and dry (CO2-dosed) partial oxidation (DPOX). Reaction runs were conducted over alumina-supported bimetallic Co–Ni promoted with CeO2 at 120 kPa and 793–893 K. Ceria promotion improved the carbon deposition resilience of the Co–Ni catalyst. Physicochemical attributes were obtained from liquid N2 adsorption, H2 chemisorption and temperature-programmed desorption runs for NH3, CO2, CH4 and C3H8. Rate behavior under ODR, DPOX and pure dry reforming could be described consistently with empirical models that are structurally similar to Langmuir–Hinshelwood type relations. Inferences from these models allowed the postulation of the same overall reaction network for the three types of reactions albeit with variation in rate-controlling steps depending on the different product species. On the whole, DPOX seemed to be a superior option for the manufacturing of syngas for downstream olefin FT production due to reduced variability in the H2:CO ratio and the closeness to unity (0.72–0.95) of the exiting syngas over the range of O2 partial pressure used.

Thermodynamic analysis of steam reforming and oxidative steam reforming of propane and butane for hydrogen production

Thermodynamic analyses of cracking, partial oxidation (POX), steam reforming (SR) and oxidative steam reforming (OSR) of butane and propane (for comparison) were performed using the Gibbs free energy minimization method under the reaction conditions of T = 250–1000 °C, steam-to-carbon ratio (S/C) of 0.5–5 and O2/HC (hydrocarbon) ratio of 0–2.4. The simulations for the cracking and POX processes showed that olefins and acetylene can be easily generated through the cracking reactions and can be removed by adding an appropriate amount of oxygen. For SR and OSR of propane and butane, predicted carbon formation only occurred at low S/C ratios (<2) with the maximum level of carbon formation at 550–650 °C. For the thermal-neutral conditions, the TN temperatures decrease with the increase of the S/C ratio (except for O/C = 0.6) and the decrease of the O/C ratio. The simulated results for SR or OSR of propane and butane are very close under the investigated conditions.

Influence of the Crystal Structure of Titanium Oxide on the Catalytic Activity of Rh/TiO2 in Steam Reforming of Propane at Low Temperature.

Solid oxide fuel cells (SOFCs) with liquefied petroleum gas (LPG) reduce CO2 emissions due to their high-energy-conversion efficiency. Although SOFCs can convert LPG directly, coking occurs easily by decomposition of hydrocarbons, including C-C bonds on the electrode of fuel cell stacks. It is therefore necessary to develop an active steam pre-reforming catalyst that eliminates the hydrocarbons at low temperature, in which waste heat of SOFCs is used. Herein, we show that the crystal structure of the TiO2 that anchors Rh particles is crucial for catalytic activity of Rh/TiO2 catalysts for propane pre-reforming. Our experimental results revealed that strong metal support interaction (SMSI) induced during H2 pre-reduction were optimized over Rh/TiO2 with a rutile structure; this catalyst catalyzed the reaction much more effectively than conventional Rh/γ-Al2 O3 . In contrast, the SMSI was too strong for Rh/TiO2 with an anatase structure, and the surface of the Rh particles was therefore covered mostly with partially reduced TiO2 . The result was very low activity.

Iron–ceria spinel (FeCe2O4) catalyst for dry reforming of propane to inhibit carbon formation

Dry reforming of propane (DRP) with CO2 was examined over iron–ceria spinel (FeCe2O4) that was synthesized on mesoporous alumina foam by the sol–gel method. The FeCe2O4/Al-F catalyst exhibited significant catalytic activity for the DRP with propane and CO2 conversions of 93% and 76%, respectively. Moreover, the redox behavior of the spinel was found to greatly reduce the deposition of carbon, which could be attributed to the oxidation of surface carbon to CO via the interaction with FeCe2O4 lattice oxygen. The FeCe2O4/Al-F catalyst with good catalytic activity, long-term stability and coke resistance may be a promising candidate for the DRP.

Synthesis and characterization of Ni2−xPdxMnO4/γ-Al2O3 catalysts for hydrogen production via propane steam reforming

Much attention has been paid to the development of environmentally friendly next-generation energy sources, such as hydrogen gas. In this context, propane steam reforming has emerged as one of the most promising approaches. Here, we report the synthesis of various Ni2−xPdxMnO4/γ-Al2O3 (x = 0, 0.01, 0.02, 0.03, 0.04, and 0.05) catalysts by sol-gel and impregnation methods and their application in steam reforming of propane (H2O/C3H8 = 6/1), doubly promoted by Pd and Ni. The introduction of Pd in Ni2−xPdxMnO4/γ-Al2O3 improved catalyst dispersion and reduction of Ni oxides. Ni2−xPdxMnO4/γ-Al2O3 catalysts showed different adsorption abilities for C3H8, CO, and H2O gases, which resulted in different catalytic behaviors in steam reforming of propane. This was presumably dependent on the Pd content, and the optimal Pd mole concentration was found to be 4%. Complete conversion of propane and the highest hydrogen selectivity were achieved over Ni1.96Pd0.04MnO4/γ-Al2O3 at 700 °C. The presence of Pd decreased the evolution of CO, which is responsible for catalyst degradation, and the catalyst maintained a high performance even after five catalytic cycles.