Reforming Of Glycerol Research Articles

Syngas production from aqueous phase reforming of glycerol–water mixture for compression ignition engine

Syngas produced from glycerol using aqueous phase reforming for nickel-based catalysts with different support materials were tested in a compression ignition (CI) engine. Experiments were conducted using nickel–alumina, nickel–lanthanum (NL), and nickel–ceria catalysts at 1:1, 1:2, 1:3, and 1:4 glycerol–water ratios and temperatures of 240°C, 260°C, and 280°C. The NL catalyst showed the highest syngas and hydrogen yield of 90.58% and 76.42%, respectively, at 1:3 ratio and 260°C. The optimized NL syngas and diesel were tested in a CI engine at 6 to 30 lpm flow rates. At 30 lpm flow, brake thermal efficiency increased by 3.15%, NOx emission was reduced by 21.22%, and smoke lowered significantly compared to diesel. The faster hydrogen combustion in syngas increased the heat release rate and cylinder peak pressure. CO and HC emissions increased at lower loads due to diluted combustion but reduced at higher loads. NL showed the best performance and emissions among the syngases due to higher hydrogen content. In summary, the NL syngas at 30 lpm showed great potential in CI engines by improving combustion and performance and reducing emissions.

An energy-efficient and cleaner production of hydrogen by steam reforming of glycerol using Aspen Plus

Hydrogen (H2) is produced in an efficient and sustainable manner using steam reforming of glycerol in this work. Two models are used to provide anticipation about how efficiently H2 can be produced: Model 1, a stoichiometric model, and Model 2, a thermodynamic model. Model 1 helps determine the water/glycerol molar input ratio and reaction pathway. The thermodynamic feasibility of Model 1 is examined using Model 2, which then determines the optimum conditions for maximal H2 generation. Model 2 produced 1275 kmol/h of H2 with an H2 mole fraction of 0.49 at 658 °C and 1 atm of pressure. The reactor's net heat load is greatly reduced through heat integration in this study. The energy required is reduced by 29.5% as compared to when no heat integration is used. The process of separating and eliminating CO2 is accomplished by employing the principles of mass and energy balance in the Aspen Plus.

Influence of alumina fixed-bed in steam reforming of glycerol for hydrogen production

In this study, hydrogen production by steam reforming was carried out in a tubular fixed-bed reactor. The influence of some operating variables such as temperature, flow rate of the feeding glycerol solution and space velocity on hydrogen production under a non-catalyzed reaction was analyzed. The results showed that the hydrogen yield increased with temperature and decreased with the space velocity. As the feedstock flow rate increased, the hydrogen yield decreased rapidly. Compared with a reference experiment without fixed-bed, the use of non-porous alumina fixed-bed showed better results. Under the best reaction conditions (900 °C and a feedstock flow rate of 0.85 g/min), 17 L/h of syngas were obtained, with a purity of about 55% of hydrogen and a production of 2.7 moles of hydrogen by mol of glycerol.

Obtaining hydrogen by steam reforming of residual glycerol from biodiesel production using Ni/La2O3-CeO2 catalysts

Ni/La2O3-CeO2 catalysts derived from perovskite-type precursors, with La1−xCexNiO3 composition (x = 0, 0.1, and 0.2), were prepared by the precipitation method, without and with the use of Pluronic F-127 surfactant. The materials were characterized using techniques including thermogravimetric analysis, nitrogen physisorption, scanning electron microscopy, X-ray diffraction, Raman spectroscopy, and temperature programmed reduction with H2. The presence of Ce and use of the surfactant resulted in samples with smaller NiO crystallites and lower reduction temperature, with the catalysts A2 (La0.9Ce0.1NiO3 + P) and A6 (LaNiO3 + P) showing the highest percentages of the LaNiO3 phase, according to XRD and TPR analyses. The glycerol conversions were high (above 96%) and similar for all the catalysts, except A5 (LaNiO3). Although the samples prepared with Ce addition did not show the best selectivity towards H2, their use led to lower carbon formation during the reaction (%C = 2.2), compared to the sample with the best catalytic performance (%C = 8.0). Overall, the materials studied here were stable and active during 5 h of reaction, with low coke formation in all cases. The findings indicated that perovskite-type catalysts synthesized with the addition of surfactant are promising for application in the steam reforming of glycerol for hydrogen production.

Carbon-neutral and carbon-negative chemical looping processes using glycerol and methane as feedstock

Carbon-negative and neutral methods to produce H2 and other syngas-derived chemicals are tested and demonstrated in this study through chemical looping reforming of methane or glycerol. A chemical looping reactor provides the heat required to reform the glycerol or methane while having inherent CO2 capture. This is achieved using dynamically operated packed beds. If the glycerol or methane is from a biological source this gives the system the potential for negative emissions. To evaluate the potential of this system, 500 g packed bed of oxygen carriers were cyclically reduced, oxidized, and used to carry out reforming experiments. The reforming process was tested at various pressure (1 – 9 bar) and temperature (600 – 900 °C). These conditions were tested at this scale for the first time. Complete conversion of glycerol is achievable with only small quantities of CH4 slip. The maximum H2 production was achieved at 1 bar and 700 °C producing a H2/CO ratio of 10, this lowered to 9 when the temperature was increased to 900 °C. Adding CO2 to the feed stream along with H2O allows for a H2/CO ratio suitable for the Fischer Tropsch (FT) synthesis. Chemical looping reforming of CH4 with steam was successfully demonstrated in a lab reactor setup at 1 and 5 bar for multiple cycles with CH4 conversion > 99% and controlled heat losses. The temperature and concentration profiles provided identical results for consecutive cycles verifying the continuity and the feasibility of the process.

Facile synthesis of fibrous Faujasite Y supported Ni (Ni/FFY) catalyst for hydrogen production via glycerol dry reforming

In this study, the dendritic structure of Ni-supported Fibrous Faujasite Y (Ni/FFY) catalyst was successfully synthesized by employing a hydrothermal-assisted microemulsion system and subsequently tested in glycerol dry reforming to produce syngas. FFY possesses high porosity due to the formation of radial wrinkle fibre observed from TEM analysis. This provides a huge amount of interparticle pores that facilitate the absorption of the molecules within the material under a minimum hindrance, hence boosting the interior surface accessibility of Ni/FFY. This exclusive morphology contributed to the enhancement in the amount of accessible Ni active sites, resulting in the good activity of Ni/FFY (C3H8O3 conversion = 56.28 %, CO yield = 70.14 %, and H2 yield = 49.80 %). The extraordinary physicochemical properties of Ni/FFY and outstanding catalytic performance in glycerol dry reforming proved its capability as a sustainable catalyst in transforming waste byproduct (glycerol) and greenhouse gas (CO2) to clean energy (H2). This finding presents a pioneering fibrous zeolite catalyst for hydrogen generation in glycerol reforming.

Facile fabrication of porous carbon nanofibers encapsulated with nanoscale exposed Ni for producing high-purity hydrogen from cheap glycerol

Transition metal nanoparticles supported on porous carbon materials as hydrothermal stable and highly effective catalysts are increasingly attracting worldwide attention. Herein, a controllable electrospinning technique was employed to prepare the promising catalysts to produce hydrogen. Different proportions of polymethyl methacrylate and nickel nitrate were introduced into polyacrylonitrile spinning solution to prepare nanoscale Ni encapsulated in porous carbon nanofiber (Ni@PCNF) through an in-situ pore-making strategy. The results show that the prepared 10 wt% Ni@PCNF catalyst possesses an enhanced specific surface area, hierarchical porous structure, and uniformly-dispersed Ni nanoparticles (∼17 nm). This porous and fibrous catalyst presents relatively high performance of producing high-purity H2 by aqueous phase reforming of glycerol compared with several reference catalysts on different supports (e.g., activated carbon fibers and γ-Al2O3) under similar reaction conditions. The selectivity and purity of H2 produced by 10 wt% Ni@PCNF catalyst at 260 °C for 1 h are nearly 100% and 93%, respectively. This is related to the moderate catalytic activity of active Ni nanoparticles encapsulated in PCNFs. By contrast, those Ni nanoparticles supported on the reference supports show a high catalytic activity and thus produce low-purity H2 due to the considerable byproducts of CH4, CO and CO2. Moreover, Ni@PCNF catalyst exhibits a good structure stability and reuse effect in comparison with reference catalysts. This work provides a roadmap for preparing effective and stable Ni-based catalysts to produce high-purity H2 from cheap glycerol through a low-temperature thermocatalysis.

Study of the photocatalytic reforming and oxidation of Glycerol over Ag–Pd/TiO2

The photocatalytic reaction of glycerol was conducted over 0.1 at. % Ag – 0.3 at.% Pd/TiO2 catalyst in order to monitor the switch over between the photo-reforming to hydrogen and CO2 and photo-oxidation to H2O and CO2. This alloy of Ag–Pd has shown to be more active than Pd for hydrogen ion reduction previously. Up to a partial pressure of about 0.2 atm. of molecular oxygen the rates of hydrogen production were mostly unaffected. There seems to be a threshold for the effect of O2 on the inhibition of hydrogen production. This is found when the ratio of dissolved molecular oxygen to surface Ti cations is about 2. Also, the order of reaction with respect to PO2 was found to be −2. Hydrogen production was found to be largely insensitive to glycerol concentrations (above 0.05 vol %) as expected from a zero order reaction kinetics in the liquid phase, where the rate is determined by surface coverage. The considerable amounts of dissolved CO2 found indicate that monitoring gas phase CO2 is not a true measurement of the photo-reaction rates. The dissolved CO2 concentration was 15–20% of the gas phase concentration of CO2 at any reaction time investigated. The fast decrease of the pH of the aqueous solution within the first 30 min points to the build up of oxidation products of glycerol. Liquid phase analysis showed the presence of formaldehyde, hydroxy acetone and ethylene glycol as the main reaction products. At high glycerol concentration the main product in the liquid phase was hydroxy acetone while at low concentrations it was formaldehyde. At low glycerol concentrations, the rise of formaldehyde concertation in the liquid phase with time was concomitant with hydrogen production, its decay with time, however, was not accompanied by further increase in hydrogen production. This is most likely because of the competition between decomposition in the presence of water (to H2 and CO2) and oxidation (to formates).

Competitiveness of hydrogen production by glycerol reforming in fixed-bed reactor: An overview of the catalytic performance, product distribution and reactant conversions

Hydrogen can be produced by thermochemical, electrolysis, and bioprocesses. The various process routes for hydrogen production are often constrained by different challenges. The bioprocess is the preferable choice since it is less energy intensive and uses fewer resources at constant temperature and pressure. Nevertheless, the bioprocess is faced with the challenges of the inconsistent rate of hydrogen production. Glycerol has lately emerged as a promising feedstock for hydrogen production, and researchers have examined its potential applications to a great extent. This mini-review focuses on evaluating the competitiveness of producing hydrogen by glycerol reforming in comparison to other processes.

Renewable syngas & hydrogen synthesis via steam reforming of glycerol over ceria-mediated exsolved metal nano catalysts

Currently, catalyst design and development has drawn much attention as results of its strategic importance in the area of energy applications particular those involving biomass conversion. This work tailored exsolution of metal catalysts through the use of ceria for enhanced structural and catalytic behaviour in steam reforming of glycerol. Aside the understanding that defects due to A-site deficiency facilitates formation of vacant sites and exsolution of metal catalysts on the B-site of perovskite systems, this work has exemplified that metals such as ceria significantly influences the exsolution and general morphological surface architecture and catalytic behaviour. The exsolved nickel catalysts anchored and socketed on a titanate support and the ceria's basic surface properties and oxygen storage-release behaviour has modified the perovskite surface chemistry and enhanced catalytic behaviour particularly deactivation due to carbon deposition and reusability. Other exsolvable dopant metal species such as Fe and Co forms alloys with nickel on the surface and the synergy between the dopant metals in the alloy yielded better results. Furthermore, in one of the catalyst systems, the most commonly observed tolerable A-site deficiency and doping limit of 2% known for SrTiO3 perovskite was overstretched by 0.5% (2.5%) thereby increasing the defect chemistry. The catalyst system with such formulation has shown a dramatic exsolution phenomenon and catalytic behaviour and robust suppression of coke deposition. CO selectivity >60% and H2 selectivity >40% was recorded with all the catalyst systems. The catalysts used in this work are useful for applications in energy and production of value added chemicals.

Perovskite modified catalysts with improved coke resistance for steam reforming of glycerol to renewable hydrogen fuel

AbstractCatalytic steam reforming of renewable feedstock to renewable energy or chemicals always goes with intense coking activities that produce carbonaceous products leading to low performance and eventual catalyst deactivation. Supported metal catalyst such as Ni/Al2O3 is known to catalysed gasification and decomposition of biomass feedstock largely for renewable fuel production with promising results. Catalyst deactivation from high carbon deposition, agglomeration and phase transformations resulting to rapid deactivation are some of the issues identified with the use of the catalyst. In this work, improvement on the coke resistance and catalytic properties of Ni/Al2O3 catalyst is sought via the use of a thermally stable and coke‐resistant perovskite La0.75Sr0.25Cr0.5Mn0.5O3‐δ (LSCM) as catalyst promoter/modifier and involving Zirconia‐doped Ceria (Ce‐Zr) as alternative support in steam reforming of pure and by‐product glycerol. The stabilizing influence of the LSCM on the Ni catalyst has improved stability against agents of deactivation with a consequent significant improvement of catalytic activity of Ni/Al2O3 in H2 production and robust suppression of carbon deposition. Particularly, the synergy between the LSCM promoter and alternative Ce0.75Zr0.25O2 support enhanced the basic and redox properties known for Ce0.75Zr0.25O2 support in contrast to the week acid centres in γ‐Al2O3 support which further improved nickel stability, catalyst–support interaction with a resultant high catalytic activity and robust coke suppression as a result of enhanced oxygen mobility. There is correlation between the product distribution, nature of coke deposited and reforming temperature as well as type of support and structural modification. Hence, integration of a robust perovskite material as a catalyst promoter and choice of support could be tailored in design and development of robust catalyst systems to improve the performance of supported metal catalysts, particularly the suppression of carbon deposition for hydrocarbon and biomass conversion to renewable fuel or chemicals.

Techno-economic analysis of methanol synthesis from syngas derived from steam reforming of crude glycerol

AbstractDue to the large amount of crude glycerol produced as a by-product by the biodiesel industry, alternative technologies for converting glycerol to value-added fuels such as syngas have been proposed. By employing four main processes, the syngas could further be used to produce methanol. The first process is steam reforming (STR) where the crude glycerol is converted into syngas. The next step is a three-unit pressure swing adsorption (PSA) system which is employed to condition the syngas into the required stoichiometric ratio. The final two process are the methanol synthesis and methanol purification processes. The effects of STR temperature, steam-to-glycerol ratio (SGR), methanol synthesis temperature and pressure were all investigated. The results obtained shows that 0.29 kgMeOH/kgCG can be obtained through this process at STR of 650 ℃, SGR of 9, and methanol synthesis temperature and pressure of 250 ℃ and 80 bar respectively. In addition, a methanol production plant capacity of 6.8 tonnes/hr of crude glycerol feed for a 20-year plant life was investigated. The result from the economic analysis carried out shows that production of methanol from glycerol is economically feasible with net present value (NPV), return on investment, (ROI), discounted payback period (DPBP) and net production cost (NPC) of $74.2 million, 17%, 4.59 years, and 85₵/kgMeOH respectively. The sensitivity analysis results show that the revenue from sales of methanol and byproducts (hydrogen and methane), the manufacturing cost, the cost of raw materials, as well as fixed capital investment (FCI) were the most sensitive economic parameters.

Syngas production from CO2 reforming of glycerol by mesoporous Ni/CeO2 catalysts

In this paper, the mesoporous Ni/CeO2 catalyst with high specific surface area was prepared by the colloidal solution combustion method and used for the production of syngas by glycerol dry reforming (GDR). The thermodynamic analysis was conducted by using a non-stoichiometric methodology based on the minimization of Gibbs's free energy. The characterization results show that the higher the Ni content, the weaker the interaction between Ni and the CeO2 support. 5Ni/CeO2 shows the most consistent Ni dispersion and uniform particle size, and it has the best catalytic activity in the GDR and the conversion of glycerol can reach 84.1 % at 750 °C. Besides, all catalysts exhibited excellent stability during the 10 h catalytic process. The temperature-programmed oxidation (TPO) results show that Ni loading ratio of 5 can reduce the production of filamentous carbon. Based on a kinetic model assuming a power law as a first-order reaction, the activation energy of the Ni-based catalyst for glycerol dry reforming was calculated.

Novel nanowire self-assembled hierarchical CeO2 microspheres loaded with nickel-based catalysts for hydrogen production from steam reforming of glycerol

The nickel-based catalysts with shape-specific CeO2 nanocrystals (hierarchical and spheres) and adjustable impregnation solvents were successfully synthesized. The synthesized Ni-CeO2 catalysts were used as the model catalyst to study the structure-dependent catalytic behavior and catalytic reaction mechanism for hydrogen production from glycerol steam reforming (GSR). Ni/CeO2-HE with the hierarchical structure and ethanol impregnation solvent obtained the strongest metal-support interaction. Electron effects because of the strong interaction between nickel and cerium dioxide promoted the formation of reducible nickel species. High nickel reduction and nickel dispersion contributed to the maximum active nickel exposure surface area, thus Ni/CeO2-HE exhibited superior glycerol conversion than other catalysts. The abundant oxygen vacancies generated due to strong Ni-CeO2 interaction facilitated the dissociation of water, thereby achieving a high yield of H2 for Ni/CeO2-HE. As a comparison, Ni/CeO2 and Ni/CeO2-E showed relatively poor catalytic activity due to lower exposed specific surface area and oxygen vacancy concentration. Moreover, the strong oxygen storage-release ability (CO-OSCC) promoted the oxidation of carbon deposition on Ni/CeO2-HE. As a result, Ni/CeO2-HE obtained good catalytic stability with no inactivation within 25 h. The study of the modulation role of Ni-CeO2 interaction on catalytic behavior can provide valuable guidelines for designing efficient catalysts for GSR.

CeO2-supported Ni and Co catalysts prepared by a solution combustion method for H2 production from glycerol: the effect of fuel/oxidizer ratio and oxygen excess

The impact of the fuel/oxidizer ratio, the fuel type and the oxygen excess in the synthesis of ceria supported Ni and Co catalysts on the physicochemical properties and activity in steam and aqueous-phase reforming of glycerol was studied.

Sorption enhanced aqueous phase reforming of biodiesel byproduct glycerol for hydrogen production over Cu-Ni bimetallic catalysts supported on gelatinous MgO

Hydrogen production from sorption enhanced aqueous phase reforming (APR) of biodiesel byproduct glycerol was studied by Ni-based monometallic and bimetallic catalysts supported on gelatinous MgO supports. Compared with Ni-based monometallic catalyst, the H2 selectivity and glycerol conversion of the Cu–Ni bimetallic catalyst were found to be increased more than 3% and 30%, respectively. Meanwhile, higher reaction temperature was found to have higher H2 yield with lower H2 selectivity. The H2 yield using the catalyst with gelatinous MgO support was 1.25 times higher than that of calcined support. Through in-situ CO2 capture, the addition of CaO to the Cu–Ni bimetallic catalyst increased more than 58.3% and 14.4% of the H2 yield and selectivity, respectively. An analysis about liquid product component indicate that the presence of CaO promote the further cleavage of the C–C bond, which further increased the conversion of glycerol. Furthermore, it was found that the presence of CaO could also improve the stability of the catalyst through the control experiments.

Insight into the effect of CeO2 morphology on catalytic performance for steam reforming of glycerol

Shape-specific CeO2 nanocrystals (spheres, rods, cubes and nanoparticles) with well-defined crystal facets were successfully synthesized and used as the support to synthesize series Ni/CeO2. Ni/CeO2 was employed as the model catalysts to study the structure dependent behavior and reaction mechanism for hydrogen production from glycerol steam reforming (GSR). The metal-support interaction was finely tuned by altering the morphology of CeO2 support, which in turn affected the exposed specific surface area of nickel and oxygen vacancy concentration. The relationship between exposed surface area of active nickel as well as surface oxygen vacancies and catalytic performance was studied. Ni/CeO2-S with the mainly exposed (111) type planes obtained the strongest metal-support interaction. Electron effects due to the strong metal-support between nickel and cerium dioxide facilitated the formation of readily reducible nickel species (Niδ+). High nickel reduction and nickel dispersion contributed to the maximum active nickel exposure surface area, thus Ni/CeO2-S showed exceptional glycerol conversion. Meanwhile, the strong Ni-CeO2 interaction resulting in abundant oxygen vacancies that facilitated the dissociation of water to produce hydrogen, thus possessing a high H2 yield. Conversely, Ni/CeO2-NR and Ni/CeO2-NC have lower exposure areas and oxygen vacancy concentrations due to the different exposed crystal planes, and therefore have relatively poor catalytic activity. Moreover, the strong oxygen storage-release ability (CO-OSC-OSCC) promoted the oxidation of carbon deposition on Ni/CeO2-S. Additionally, carbon deposition was mainly the filamentous carbon growing towards the periphery, hence, Ni/CeO2-S obtained up to 25-h catalytic stability. The study of the regulatory role of Ni-CeO2 interaction on catalytic behavior can offer worthwhile direction for designing high-efficiency GSR catalysts.

The influence of phase purity on the stability of Pt/LaAlO3 catalysts in the aqueous phase reforming of glycerol

Aqueous phase reforming (APR) of waste oxygenates offers the potential for sustainable hydrogen production. However, catalyst stability remains elusive, due to the aggressive hydrothermal conditions employed. Herein, we show that the catalytic performance and stability of Pt supported on LaAlO3 catalysts for glycerol APR is strongly influenced by the phase purity of LaAlO3. Calcination of the support at 700 °C produces the LaAlO3 perovskite phase and an amorphous lanthanum carbonate phase, which can be removed by calcination at higher temperature. Catalysts comprised of phase pure LaAlO3 were notably more active, with a support calcination temperature of 1100 °C resulting in 20.4% glycerol conversion (TOF 686 h−1) in a 2 h batch reaction. Interestingly, all the catalysts, regardless of LaAlO3 phase purity, eventually transform into Pt/LaCO3OH-AlO(OH) during reaction, but only in the presence of evolved carbon dioxide, itself produced from glycerol reforming. Studies using simulated reaction products showed that organic acid products (lactic acid), in the absence of CO2, facilitated La leaching and loss of crystallinity. A carbonate source (CO2) is essential to limit La leaching and form stable Pt/LaCO3OH. Pt supported on LaCO3OH and AlO(OH) are stable and active catalysts during APR reactions. Yet, the rate of perovskite phase decomposition strongly influences the final catalyst performance, with the initially phase impure LaAlO3 decomposing too quickly to facilitate Pt redistribution. LaAlO3 calcined at higher temperatures evolved more slowly and consequently produced more active catalysts.

Steam reforming of bio-alcohols over Ni-M (Cu, Co, Pt)/MCF-S (MgO, La2O3, CeO2) for renewable and selective hydrogen production: Synergistic effect of MCF silica and basic oxides on activity and stability profiles

In the current investigation, highly active, and stable catalyst-support systems were developed by employing the benefits of the 3D mesoporous arrangement of MCF silica and O2− Lewis basic sites of MgO, La2O3, and CeO2 in a single system for renewable and selective H2 production via steam reforming (SR) of bio-alcohols, viz., ethanol (SRE), glycerol (SRG), n-butanol (SRB), and ethylene glycol (SREG). The impact of aging time [24, 48, and 72 h ] on structural and surface features of MCF silica was also investigated to develop novel type of mesoporous materials with the best textural properties, viz., Cu-Ni-Co/MCF-MgO for SRE, Ni-Cu/MCF-La2O3 for SRG, Pt-Ni-Cu/MCF-La2O3 for SRB and Ni-Cu/MCF-CeO2 for SREG which were characterized by several physio-chemical techniques; for instance, BET, H2-TPD, H2-TPR, TGA, XRD, TEM, SEM, EDX as well as high-resolution XPS analysis. The efficacy of the combination of MCF silica with basic metal oxides was evident from the results showing nearly complete reactant conversion, no coke formation, high selectivity (>84 % H2 yield), and long-term stability beyond 680 h (> 68 h time on stream (TOS) for one cycle over > 10 cycles) for all bio-alcohols whereas MCF silica without any basic metal oxides, i.e. Ni-Cu/MCF was stable only up to ≤ 64 h (≤ 16 h TOS for one cycle up to ≤ 4 cycles) due to the absence of O2− Lewis basic sites leading to coking. Such a huge difference in catalytic stability between MCF-S (MgO, La2O3, CeO2) and Ni-Cu/MCF catalysts clearly justifies the synergistic effect of the 3D mesoporous structure of MCF silica and O2− Lewis basic sites on high metal dispersion, strong metal-support interaction (SMSI), coke inhibition. It proved their efficacy as potential commercial SR catalysts for sustainable H2 production from bio-alcohols. Finally, catalytic reaction mechanisms were developed for SRE, SRG, SRB, SREG and intrinsic reaction kinetics were studied over their corresponding catalyst-support systems in the absence of external mass transfer and intra-particle diffusion resistancs. The apparent activation energies for SRE, SRG, SRB, and SREG were calculated as 7.2, 11.2, 10.5, and 12.1 kcal/mol, respectively.

Sorption-enhanced chemical looping steam reforming of glycerol with CO2 in-situ capture and utilization

Hydrogen production from chemical looping steam reforming using an oxygen transport catalyst is definitely enhanced by CO2 in-situ capture, which shifts the chemical equilibrium and reduces the energy demands. The utilization of CO2 from this process as a reactant for chemicals and fuels could help to improve economic reasons and mitigate its impact on climate. In this study, we proposed a sorption-enhanced chemical looping steam reforming of glycerol to realize the synergetic capture and conversion of CO2 in one integrated chemical looping hydrogen production process. The process is characterized to usethe oxidized NiO/NiAl2O4 as a steam reforming catalyst, the reduced NiO/NiAl2O4 as a CO2-CH4 dry reforming catalyst, and the inexpensive dolomite as a CO2 sorbent. The surface carbon that would deactivate the catalyst is combusted by air after CO2-CH4 dry reforming and the Ni on the catalyst is re-oxidized. The coupling of these different processes of chemical looping steam reforming, CO2 in-situ capture, dolomite decomposition and CO2 in-situ utilization, results in simultaneous generation of high purity hydrogen and syngas. The results demonstrated that hydrogen of above 92.5% was one-step generated and CO2 was decreased to zero in the pre-CO2 breakthrough periods. The reduced NiO/NiAl2O4 catalysts favored the CO2-CH4 dry reforming at 850 °C. The syngas of H2-to-CO molar ratios of 0.8–1.1 through the conversion of CO2 from in-situ extraction of the absorbed CO2 dolomite, was produced. The NiO/Al2O4 with 15 wt% NiO gave the highest hydrogen and syngas yields, and maintained high performance for the proposed system. The catalysts and dolomite exhibited good stability with no obvious loss of activity in 10 cycles.