Reforming Of Glycerol Research Articles

Understanding the role of SrO-ZrO2 mixed oxide support for Co3O4 based catalysts towards H2 production from steam reforming of glycerol

Cobalt dispersed on SrO-ZrO2 mixed oxide catalysts were prepared by varying the ratios of Sr and Zr. These catalysts were studied for hydrogen production from glycerol steam reforming. The physico-chemical characteristics of the catalysts were investigated by different techniques. Among all the catalysts, 15 %Co dispersed on SrO-ZrO2 with a 1:1 ratio of Sr and Zr catalyst exhibited the best activity with complete transformation of glycerol into gaseous products (H2, CH4, CO and CO2) with 73 % hydrogen yield. The catalyst activity varied with the change in Sr-Zr ratio where the redox properties of ZrO2 improved the water gas shift reaction in glycerol steam reforming. The characterization results reveal that the high activity of the catalyst is mainly due to the presence of a greater number of octahedral sites, small Co particles, Sr-Zr-Co-O solid solution, strong metal support interactions, and basicity. The catalyst is highly stable as it showed consistent performance during time on stream analysis conceded for a period of 50 h.

Thermocatalytic routes and reactor strategies for valorization of biodiesel-derived glycerol to fuels

Glycerol is an oversupplied commodity from biodiesel production with beneficial properties for the synthesis of versatile utility biochemicals. The functional properties of glycerol with three hydroxyl groups could be tailored toward producing fuels such as hydrogen, syngas, C1-C3 hydrocarbon fuel, bio-oil and methane. This study elucidates the reported thermochemical pathways such as pyrolysis, gasification, combustion, steam and aqueous reforming, and supercritical water gasification for fuel production from biodiesel-derived glycerol. The mechanism of these pathways, process conditions, catalytic integration, and limitations were investigated. Also, reactor strategies such as fixed bed reactors, fluidized bed, and solar reactor strategies used for the thermochemical valorization of glycerol was discussed. The studies revealed that hydrogen up to 70% yield could be generated from glycerol using noble metals and nickel-based catalysts. Catalyst deactivation due to coking could be minimized by the addition of alkaline metals, which discourages methanation reaction. Reaction parameters such as temperature, catalyst amount, time on stream, and glycerol/water or steam ratio influence the product distribution. The glycerol steam reforming is more energy-intensive and requires temperatures in the range of 450–1000 °C, whereas the aqueous reforming is propagated in the range of 180–250 °C. The circulating fluidized bed reactors limit coking due to self-regeneration of the catalysts in situ, however, they are cost-intensive. Life cycle assessment analysis revealed that supercritical water reforming (SCWR) of glycerol offers a sustainable pathway to reduce CO2 by 95% and integration of SCWR in biodiesel plants to produce hydrogen for heating can realize a net present value between 7.70 and 15.70 million USD. Further studies to analyze the economic impact of the individual pathways to optimize the production of fuels from glycerol are required. It is hoped that this study will engage industries and researchers to increasingly use glycerol as a substrate for the production of fuels for transportation.

Photoelectrochemical reforming of glycerol by Bi2WO6 photoanodes: Role of the electrolyte pH on the H2 evolution efficiency and product selectivity

Photoreforming of biomass derivatives is a promising strategy for the production of green hydrogen and chemicals. Herein, nanocrystalline Bi2WO6 photoanodes were applied for the first time for the conversion of glycerol in different pHs. Different from TiO2 photoanodes, the photocurrent for Bi2WO6 films is relatively independent of the applied potential, which is attributed to the preferential glycerol oxidation in detriment of water oxidation. Impedance measurements reveal that photocurrent is limited by the charge transfer on the Bi2WO6 surface and is partially inhibited by the poor desorption of glycerol oxidation products. At pH 6, photocurrents up to 0.69 mA cm−2 are reached with a faradaic efficiency for H2 evolution of 100% and 41% selectivity for formate production. In acid media, this selectivity increases to 88%, but the photocurrent decreases 50%. In alkaline media, glycerol oxidation is facilitated and photocurrents up to 0.80 mA cm−2 are reached at the cost of poor product selectivity.

Evaluation of Porous Honeycomb-Shaped CuO/CeO2 Catalyst in Vapour Phase Glycerol Reforming for Sustainable Hydrogen Production

This study presented an optimisation study of two-stage vapour-phase catalytic glycerol reforming (VPCGR) using response surface methodology (RSM) with a central composite experimental design (CCD) approach. Characterisation through Brunauer–Emmett–Teller analysis (BET), small-angle X-ray scattering (SAXS), scanning electron microscopy coupled with energy dispersive X-ray analysis (SEM-EDX), atomic force microscopy (AFM) and particle X-ray diffraction (PXRD) were carried out to understand the physiochemical activity of the honeycomb morphology CuO/CeO2 catalyst. Notably, in this study, we achieved the desired result of glycerol conversion (94%) and H2 production (81 vol.%) under the reaction condition of Cu species loading (10 wt.%), reaction temperature (823 K), WHSV (2 h−1) and glycerol concentration (15 wt.%). From the RSM analysis, an optimum predicted model for VPCGR was obtained and further integrated into Microsoft Excel and Aspen Plus to perform an energy analysis of the VPCGR plant at a scale of 100 kg h−1 of glycerol feed. As a whole, this study aimed to provide an overview of the technical operation and energy aspect for a sustainable frontier in glycerol reforming.

Study of the hydrogen production by the aqueous phase reforming of glycerol over Ni-based catalysts

The present work studied the effects of loading Fe, Ca, and the impurities of glycerol on the Ni/Al catalytic behavior in the aqueous phase reforming (APR) of glycerol to obtain renewable hydrogen.

Raquel Raso - Study of the hydrogen production by aqueous phase reforming of glycerol over Ni-based catalysts

Study of the hydrogen production by aqueous phase reforming of glycerol over Ni-based catalysts

Aqueous-Phase Glycerol Conversion over Ni-Based Catalysts Synthesized by Nanocasting

A morphological strategy consisting of nanocasting synthesis of nickel aluminate spinel precursor was addressed. Two nanocasted catalysts were synthesized involving different template-removal procedures (i.e., Teflon-assisted calcination vs. NaOH washing) for spinel recovery. As a reference, spinel NiAl2O4 supported by SBA-15 and bare nickel aluminate spinel were selected. The obtained solids were characterized in detail, examining their textural, acid–base, structural and compositional characteristics, either in the calcined or reduced forms. The as-obtained catalysts’ performance was evaluated in the aqueous-phase reforming of glycerol at 235 °C and 35 bar. Exhausted samples were also characterized to enlighten changes in catalyst properties during the aqueous-phase reaction. NiAl/SBA-15 and NiAl-NCF catalyst showed very poor catalytic performance for the glycerol transformation. NiAl-NCN catalyst presented improved activity with respect to NiAl, with a 20% higher hydrogen production rate but, as a drawback, higher methane formation for a whole range of glycerol conversions. Exhausted catalyst indicated nickel oxidized in liquid phase reaction.

Electrochemical reforming of glycerol into hydrogen in a batch-stirred electrochemical tank reactor equipped with stainless steel electrodes: Parametric optimization, total operating cost, and life cycle assessment

The electrochemical reforming of glycerol was carried out in a batch-stirred electrochemical tank reactor equipped with stainless steel electrodes. A response surface methodology constituted by a Face-Centered Central Composite Design was performed to establish the optimal operational conditions to produce hydrogen. Studied parameters were glycerol concentration (CG), current intensity (I) and temperature (T), while chosen responses were hydrogen and oxygen concentrations (CH2 and CO2). A maximum CH2 (79.18 mg/L) and minimum CO2 (46.24 mg/L) with a global desirability of 67%, were achieved at multi-optimal conditions, including CG, = 3.46 mol/L, I = 5.21 A, and T = 70 °C. All studied parameters were significant for both chosen responses (ηCH2 and ηCO2) since all values of the sensitivity index were higher than 0.5. The analysis of interaction between parameters suggests than CG and T simultaneous increase will bring a decrease in CH2. The experimental data were fitted to a quadratic polynomial surrogate model, with correlation coefficients of 0.9801 and 0.9967 for ηCH2 and ηCO2, respectively. The reduced root-mean-square error was 0.065 and 0.054 for ηCH2 and ηCO2, respectively. This suggests a successful optimization of the BSETR operational parameters. The hydrogen production process assessed in this work, is a promising green energy technology that uses waste glycerol as a carbon-based fuel and a low-cost anode material (7.5 USD¢/kg H2) as stainless steel. The carbon footprint of the hydrogen production by the optimized process is 0.192 kg CO2 eq and this can be reduced 92.1% when using a solar photovoltaic system to energize the electrodes.

Synergistic effect of photo-thermal catalytic glycerol reforming hydrogen production over 2D Au/TiO2 nanoflakes

Constructing efficient photothermal catalysts and understanding their photothermal synergistic effects for solar-driven conversion of biomass derivatives towards clean energy carriers are essential in the development of renewable energy and waste disposal. In this study, Au nanoparticles loaded on TiO2 nanoflakes were synthesized as photothermal catalysts for bio-derived glycerol photothermal reforming hydrogen production. The results found that the generation of photogenerated carriers is a crucial process in the photothermal reforming of glycerol. In particular, the hot electrons excited by plasmonic Au nanoparticles did not participate in the hydrogen production reaction through neither direct nor indirect transfer. Instead, the hot carriers promoted the intermolecular collisions between reactants through thermalization. In addition, such generated local heat could reduce the semiconductor impedance and improve the migration efficiency of photogenerated carriers, resulting in an efficient conversion of gas phase intermediates. As obtained, photothermal enhanced reforming can improve hydrogen yield by 58%, while the hydrogen generated constant and the absorption equilibrium constant was calculated as 2.38 mmol∙g−1∙h−1 and 7.00 mL∙mmol−1.

Boosting hydrogen production from steam reforming of glycerol via constructing moderate metal-support interaction in Ni@Al2O3 catalyst

In this manuscript, the relationship between metal-support interaction and the catalytic performance for hydrogen production from steam reforming of glycerol (GSR) over Ni-Al2O3 based catalysts was studied. Pure core–shell structured Ni@Al2O3 and supported Ni/Al2O3 with a fixed medium-sized nickel particle were synthesized without the other additional components to eliminate the influence of other factors. And then the nickel-alumina interaction of Ni@Al2O3 was tuned precisely and the regulatory mechanism of nickel-alumina interaction on catalytic activity was elaborated. The strong nickel-alumina interaction over Ni/Al2O3 and Ni@Al2O3 with high calcination temperature resulted in the formation of NiAl2O4, which was unfavorable to the reduction of nickel species to obtain the more active nickel. Consequently, the poor catalytic performance was caused. The moderate nickel-alumina interaction of Ni@Al2O3 promoted the exposure of the maximum area of active nickel and obtained higher turnover frequency (TOF). Thus, Ni@Al2O3 showed the high catalytic performance in GSR. Additionally, metal-support interaction affected the morphology and growth mechanism of coke deposition. For Ni@Al2O3 with moderate nickel-alumina interaction, the formation of carbon deposition followed the ‘tip-growth’ pattern, and the filamentous coke was mainly formed on catalysts. Conversely, ‘base-growth’ pattern was followed on Ni/Al2O3 with strong nickel-alumina interaction to form mainly encapsulated coke. The research findings of the regulatory role of interaction between nickel and alumina on catalytic performance will provide valuable guidelines for designing effective GSR catalysts.

Nickel encapsulated in silicalite-1 zeolite catalysts for steam reforming of glycerol (SRG) towards renewable hydrogen production

Valorisation of crude glycerol via steam reforming, i.e., SRG, is a promising method to produce sustainable hydrogen. However, catalyst deactivation under harsh SRG conditions is still a main challenge which hinders the further development of practical SRG. In this work, the encapsulated Ni catalyst in siliceous silicalite-1 zeolite (Ni@Si-1) were developed to show the improved performance and enhanced anti-deactivation potentials in catalytic SRG as compared with the conventional impregnated Ni catalysts (i.e., Ni/Si-1). Importantly, the post-synthetic treatment of Ni@Si-1 using TPAOH solution formed the encapsulated Ni catalyst with the mesoporous hollow structure (i.e., Ni@HolSi-1), which demonstrate even better performance in SRG with glycerol conversion of >95%, H2 yield of ~70%, H2/CO2 molar ratio of >2.33 and CO/CO2 molar ratio of <1 at 750 °C. Specifically, highly dispersed ultrasmall encapsulated Ni particles were retained within the hollow crystals of siliceous silicalite-1, as confirmed by XPS and HRTEM characterisation. The activation energy for glycerol conversion over Ni@HolSi-1 (i.e., Ea = ~ 19 kJ mol−1) was much lower than that of Ni/Si-1 and Ni@Si-1. 100-h longevity tests over the three catalysts were investigated at 750 °C, and the Ni@HolSi-1 catalyst exhibited an excellent stability and activity, as well as insignificant coke deposition, which could be due to the enhancement of highly dispersed yet accessible Ni NPs within the hollow Si-1 crystals. The findings of the work show the promise of the encapsulation strategy and mesoporous zeolites for developing the future reforming catalysts.

Progress and Recent Strategies in the Synthesis and Catalytic Applications of Perovskites Based on Lanthanum and Aluminum.

Lanthanum aluminate-based perovskite (LaAlO3) has excellent stability at high temperatures, low toxicity, and high chemical resistance and also offers wide versatility to the substitution of La3+ and Al3+, thus, allowing it to be applied as a catalyst, nano-adsorbent, sensor, and microwave dielectric resonator, amongst other equally important uses. As such, LaAlO3 perovskites have gained importance in recent years. This review considers the extensive literature of the past 10 years on the synthesis and catalytic applications of perovskites based on lanthanum and aluminum (LaAlO3). The aim is, first, to provide an overview of the structure, properties, and classification of perovskites. Secondly, the most recent advances in synthetic methods, such as solid-state methods, solution-mediated methods (co-precipitation, sol–gel, and Pechini synthesis), thermal treatments (combustion, microwave, and freeze drying), and hydrothermal and solvothermal methods, are also discussed. The most recent energetic catalytic applications (the dry and steam reforming of methane; steam reforming of toluene, glycerol, and ethanol; and oxidative coupling of methane, amongst others) using these functional materials are also addressed. Finally, the synthetic challenges, advantages, and limitations associated with the preparation methods and catalytic applications are discussed.

Perovskite-Based Phase Transition Sorbents for Sorption-Enhanced Oxidative Steam Reforming of Glycerol

Perovskite-Based Phase Transition Sorbents for Sorption-Enhanced Oxidative Steam Reforming of Glycerol

Hydrogen production by glycerol reforming in a two-fixed-bed reactor

A two-stage fixed bed system was used in the hydrogen production from glycerol reforming. The calcined dolomite catalyst was used in the first fixed bed, and the Nickel-based catalyst was used in the second fixed bed to produce hydrogen from the glycerol steam reforming. The results showed that the hydrogen yield and carbon conversion gradually increased with the temperature increasing. When the temperature exceeded 800 °C, the growth rate of hydrogen yield and carbon conversion decreased. As the space velocity increased, the hydrogen yield and carbon conversion gradually decreased. When the space velocity was greater than 2 h−1, the decline rate of hydrogen yield and carbon conversion decreased rapidly. As the water-to-carbon ratio (S/C) increased, the hydrogen yield and carbon conversion gradually increased. The growth rate of hydrogen yield and carbon conversion became smaller when the S/C was more than 5. Compared with the single-stage fixed-bed reactor, the utilization of two-stage fixed-bed catalytic reaction system can not only increase the hydrogen yield and carbon conversion, but extend the life of the Nickel-based catalyst. Under the optimal reaction conditions, the hydrogen yield is as high as 84.3%, and the carbon conversion is as high as 88.23%.

Parametric study on electrochemical reforming of glycerol for hydrogen production

Hydrogen production by electrochemical reforming of glycerol was investigated in this study. Within this scope, the performance of the system under different operating conditions was evaluated by parametric studies and optimum operating conditions were determined. The effects of membrane type, membrane pre-treatment procedure and temperature were investigated. System performance was examined also with long-term tests. The formation of hydrogen at the cathode was determined by analyzing the product gases by gas chromatography. Optimum condition for maximum hydrogen production was obtained with the Zn/Zn electrode pair in the presence of 0.4 M glycerol and 0.04 M H2SO4 at the anode side, 0.04 M H2SO4 at the cathode side and with pre-treated Nafion XL membrane. As the result of performance tests, room temperature and 2 V potential were found to be the most suitable operating conditions.

Steam reforming of monohydric alcohols and polyalcohols: Influence of single or multiple hydroxyl group(s) on nature of the coke

Alcohols like ethanol and glycerol have been extensively investigated as potential feedstock for on-site hydrogen production by steam reforming. The varied number of hydroxyl group in the alcohols inevitably affects the reaction intermediates generated and eventually properties of coke formed. In this study, four alcohols (ethanol, ethylene glycol, 1-propanol and glycerol) with the single or multiple hydroxyl groups were steam reformed, focusing on the influence of the hydroxyl group on the properties of the coke. The research results showed that steam reforming of ethanol and glycerol produced more coke than that in steam reforming of 1-propanol or ethylene glycol, while the Ni/SBA-15 catalyst deactivated to a higher extent in steam reforming of ethylene glycol or glycerol with multiple hydroxyl group, due to the coke of varied properties. The coke produced by steam reforming of ethanol and 1-propanol contained more defective structures but more aromatic. However, the generated coke from the steam reforming of ethylene glycol and glycerol had more aliphatic structures, especially in that from ethylene glycol. On the other hand, the carbon nanotubes formed by the steam reforming of ethanol or 1-propanol had thin wall thickness and smooth surface, while that in steam reforming of ethylene glycol and glycerol had thick wall and very rough surface, resulting from the distinct reaction intermediates formed.

CFD modelling of supercritical water reforming of glycerol for hydrogen production

Abstract Glycerol, as a main by-product of biodiesel synthesis, can be used in a large variety of applications including food, personal care, pharmaceutical and chemical industries However, due to the large production of biodiesel, the glycerol market was depressed. The conversion of glycerol into an energy carrier (syngas or hydrogen) could be a very interesting route to providing value as a renewable energy source. The reforming of glycerol leads to an almost complete conversion and very high carbon-to-gas efficiency with short residence time. In this work, the performances of packed bed reactor for hydrogen production from glycerol in supercritical conditions, by using a Ni-based catalyst supported on Al2O3 and SiO2, through CFD modelling in three-dimensions were studied. The parameters of kinetic model were determined by using an optimization method to fit the experimental data. The developed model was been validated based on experimental results published in literature for three different feed concentration of glycerol of 5, 10 and 20 wt% (R2 = 0.969). Varying the reaction temperature, between 500 and 800 °C, and residence time, between 1.5 and 10 s, the concentration of hydrogen increased with increasing the temperature and decreasing the residence time. At high temperature, the hydrogen can achieve a concentration of 65% and the present of methane is less than 5% and carbon monoxide maintain lower concentration. The simulation results show that high hydrogen yield can be obtained in short residence time with conversion of glycerol almost completed.

Increasing bio-hydrogen production-based steam reforming ANFIS based model and metaheuristics

Some parameters directly affect the steam reforming and the determination of their optimal values will definitely produce an increment in the outcomes of the bio-hydrogen. Therefore, the main goal of the presented paper is to improve the bio-hydrogen production-based steam reforming using fuzzy modelling and modern optimization. Three input controlling parameters are varied to improve the output performance of the steam reforming process. These parameters are the reformer temperature (RT), steam-to-fuel ratio (SFR), and biodiesel-to-glycerol ratio (BGR). In the design of steam reforming of glycerol/biodiesel mixture, the experiments were carried out at predefined set of values for the three inputs. The RT (°C), SFR and BGR (%) are assigned values of [500, 650, 800], and [0, 10, 20], respectively. The proposed strategy is composed of two sequential stages. First, by using the experimental data, a robust fuzzy model to simulate the output performance of steam reforming of glycerol and biodiesel fuel mixtures has been created. The results showed that the proposed model is superior to the RSM. Second, the optimal input controlling parameters are determined by marine predators algorithm (MPA). The results of the proposed MPA proved the robustness of the methodology in comparison to other recent optimizers. The results of the proposed strategy showed that the hydrogen production has increased by 5.74% and 4.8 % compared to the experimental and the RSM methodology, respectively. In conclusion, the findings of the proposed strategy illustrate the superiority in comparison to the experimental work and the RSM.

Nanoarchitectonics of Ni/CeO2 Catalysts: The Effect of Pretreatment on the Low-Temperature Steam Reforming of Glycerol.

CeO2 nanosphere-supported nickel catalysts were prepared by the wetness impregnation method and employed for hydrogen production from glycerol steam reforming. The dried catalyst precursors were either reduced by H2 after thermal calcination or reduced by H2 directly without calcination. The catalysts that were reduced by H2 without calcination achieved a 95% glycerol conversion at a reaction temperature of only 475 °C, and the catalytic stability was up to 35 h. However, the reaction temperature required of catalysts reduced by H2 with calcination was 500 °C, and the catalysts was rapidly inactivated after 25 h of reaction. A series of physicochemical characterization revealed that direct H2 reduction without calcination enhanced the concentration of oxygen vacancies. Thus, the nickel dispersion was improved, the nickel nanoparticle size was reduced, and the reduction of nickel was increased. Moreover, the high concentration of oxygen vacancy not only contributed to the increase of H2 yield, but also effectively reduced the amount of carbon deposition. The increased active nickel surface area and oxygen vacancies synergistically resulted in the superior catalytic performance for the catalyst that was directly reduced by H2 without calcination. The simple, direct hydrogen reduction method remarkably boosts catalytic performance. This strategy can be extended to other supports with redox properties and applied to heterogeneous catalytic reactions involving resistance to sintering and carbon deposition.

Aqueous-phase reforming of glycerol over Pt-Co catalyst: Effect of process variables

This study examined the influence of process variables (glycerol concentration in feed, coupled temperature/pressure and space velocity) in the catalytic performance in the APR of glycerol over 0.3Pt/CoAl catalyst in a continuous fixed-bed reactor in order to maximize the production of H2. The effect of glycerol concentration in the feed was studied from 5 to 20 wt%, the coupled temperature/pressure varied from 225 °C/25 bar to 260 °C/50 bar and the spatial velocity was changed from 0.68 to 17 h-1. Our results reflected that H2 production was favored at higher reaction temperature/pressure (3.62 vs. 2.49 molH2/molGly-converted, at the most severe and mild conditions, respectively), lower WHSV (3.89 vs. 1.27 molH2/molGly-converted, at the lowest and highest space velocity, respectively) and more diluted feedstocks (3.95 vs. 1.44 molH2/molGly-converted, at the most diluted and concentrated freestreams, respectively). A threshold value at 10 wt% glycerol was found for the ratio of dehydrogenation to dehydration liquid products. The post-reaction catalyst was also characterized by several techniques, showing that Co leaching was the major drawback, especially at the mildest operation conditions, while carbonaceous deposits are negligible.