Aqueous Phase Reforming Of Glycerol Research Articles

Improvement of hydrogen production via aqueous phase reforming of glycerol with Ni-Co catalysts synthesized through controlled urea matrix combustion

The effect of synthesis variable control during the combustion of urea in solution to obtain a Ni-Co/γ-Al2O3 catalyst with a low metallic loads for producting hydrogen by reforming glycerol was studied. Catalysts with the same urea/metal molar ratio but synthesized by controlled or uncontrolled urea matrix combustion were compared. It has been observed that adopting a urea/metal molar ratio between 2 and 6 and a heating rate of 10 °C∙min−1 results in a catalyst with an active surface and high Ni-Co interaction. This leads to significant improvements in H2 yield (from 34 to 50%), glycerol conversion (from 35 to 50%), and H2 selectivity (from 96 to 99%), while maintaining stability during 420 min of reaction. The repeatability of controlled synthesis has shown differences in results of less than 2%. Controlled synthesis is an attractive approach for scaling up the process for treating glycerinous waters, effluents in biodiesel plants.

Aqueous-phase Reforming of Glycerol using Cu-Ni Bimetal Catalyst Supported over Coconut Shell Activated Carbon

The increasing generation of glycerol as a waste from biodiesel production calls for its various consumptions, especially in producing industrial chemicals. However, the focus of popular studies in this process is on using noble metals as the catalyst. It should be shifted to a low cost and abundant element to ensure sustainability. Therefore, this study uses activated carbon from coconut shells to support a bimetal catalyst copper-nickel in converting glycerol into value-added products. The catalyst was synthesized via the wet impregnation method and was characterized using scanning electron microscopy-energy dispersive X-ray spectroscopy, Fourier-Transform infra-red spectroscopy, and a surface area analyser. It was revealed that the BET surface area (582 m2/g) is smaller than the pristine carbon because of the exposure to high temperature during calcination. The average pore size (1.7 nm) is also smaller than the coconut shell carbon due to the same effect. The surface functional groups mainly consist of carboxylic acids that is known to contribute to the hydrogenolysis of glycerol. At 20 wt% initial glycerol concentration, 20 bar and 200 °C, acetic acid, propylene oxide, carbon monoxide and acetaldehyde were detected as the products. A possible mechanism was proposed considering the aqueous-phase reforming of glycerol and the dehydration process. The optimum operating conditions in this case are 20 wt% initial glycerol concentration, 25 bar and 200 °C. More studies are needed to evaluate the reactions involved in aqueous-phase reforming of glycerol using the Cu-Ni doped on coconut shell activated carbon. In conclusion, glycerol can be converted to valuable chemicals under mild conditions by using the cost-effective catalyst.

The effect of flow conditions on the activity and stability of Pt/LaAlO3 perovskite catalyst during aqueous phase reforming of glycerol

We present a systematic investigation of key reaction parameters (WHSV, hydrogen/gas–liquid ratio, time, pressure) on the activity and stability of Pt/LaAlO3 perovskite catalysts during the aqueous phase reforming of glycerol at 240 °C and 40 bar. Reactor configuration (batch vs continuous) strongly influences product selectivity. While batch conditions promote lactic acid production which contributes to the complete decomposition of LaAlO3 phase and activity loss within 6 h, flow conditions facilitate the hydrogenation of hydroxyacetone and 1,2-propanediol intermediates to improve progression along the desired reforming pathway. After an initial induction period, associated with partial perovskite transformation into LaCO3OH and doubling of Pt nanoparticle size, catalysts remained stable over an extended 30 h experiment. Catalyst activity increased with increasing gas–liquid phase ratio (co-feeding of argon) and particularly after decreasing the reaction pressure into the 2-phase region (20 bar), resulting in 5-fold increase in conversion and complete retention of the LaAlO3 phase.

Carbon-negative hydrogen: aqueous phase reforming (APR) of glycerol over NiPt bimetallic catalyst coupled with CO2 sequestration

Carbon-negative H2 can be produced by coupling APR technology with CO2 sequestration. APR of glycerol over NiPt bimetallic catalyst coupled with CCUS can produce H2 with negative GHG emissions (–57 CO2 eq. per kg H2) using renewable electricity.

Life cycle analysis of hydrogen production from aqueous phase reforming of glycerol

In the realm of climate change mitigation, hydrogen emerges as a versatile and eco-friendly energy carrier, promising significant contributions to sectoral decarbonization. This study investigates glycerol as a feedstock for hydrogen production through aqueous-phase reforming (APR). Employing experimental data, an artificial neural network (ANN) model is developed to simulate the process, optimizing hydrogen yield under steady-state conditions. Material and energy balances enable a life cycle analysis (LCA) at a scale of 100 Nm3 H2/h, considering the synthesis subprocess of the catalyst. The LCA, using both midpoint and endpoint approaches, is compared with eight alternative hydrogen production methods. Despite variations in reporting, comparison revealed the studied process as advantageous in five of the 18 midpoint categories, particularly in marine ecotoxicity, water depletion, fossil depletion, agricultural land occupation, and metal depletion. These findings underscore the potential of glycerol APR as an environmentally sustainable option for hydrogen production.

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.

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.

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.

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.

Lignin depolymerization and monomeric evolution during fast pyrolysis oil upgrading with hydrogen from glycerol aqueous phase reforming

• Upgrading of Bio-oil with hydrogen from glycerol aqueous phase reforming. • 34.6% of lignin derived compounds were converted to hydrocarbon. • Pt/C and H-ZSM-5 catalysts were effective for hydrodeoxygenation reaction. • n-Decane as a co-solvent prevents condensation reaction. • Series of demethoxylation, hydrogenation, and hydrodeoxygenation were observed. A novel approach to Fast Pyrolysis Oil (FPO) upgrading with hydrogen from glycerol aqueous phase reforming (APR) was conducted in a biphasic solution. FPO contains both monomer and polymer compounds which rich in oxygen, giving high acidity and low stability. Hydrogen demanding reaction of depolymerization and hydrodeoxygenation (HDO), often called upgrading, is required to improve FPO properties by converting these compounds to hydrocarbon monomers. APR reaction of glycerol where glycerol is reacted with water to produce hydrogen is one of the renewable choices to obtain hydrogen. Prior to upgrading of FPO, catalyst screening and reaction optimization were studied using phenol as a model compound. Upgrading of FPO with in situ glycerol APR was conducted with Pt/C, facilitating hydrogen production (APR) and utilization (hydrogenation), and H-ZSM-5, facilitating dehydration reaction. n-Decane was added to the reaction as a co-solvent to prevent the condensation of the non-polar fragments of FPO which led to coke formation. Upon upgrading the weight average molecular weight (Mw), polydispersity index (PDI), and oxygen to carbon (O/C) ratio of FPO decreased. The highest hydrocarbon yield (7.7% FPO basis or 34.6% lignin basis) was obtained by combining Pt/C and H-ZSM-5 catalysts with n-decane as a co-solvent. Evidence of progressive depolymerization and sequential demethoxylation, hydrogenation, and deoxygenation during upgrading were observed in the products.

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.

Hydrogen production from aqueous phase reforming of glycerol over attapulgite-supported nickel catalysts: Effect of acid/base treatment and Fe additive

In this paper, a series of nickel-based catalysts supported on modified attapulgite (ATP) by acid (citric acid and EDTA) and base (NaOH) were prepared and applied to the aqueous phase reforming of glycerol (APRG). The modified ATP (MA) and as-prepared catalysts were detected using N2 adsorption-desorption, ICP-OES, XRD, FT-IR, SEM-EDS, HRTEM, XPS, H2-TPR, NH3-TPD. The results manifested that the acid/base treatment of ATP significantly increased the surface area and pore volume, enhanced the metal-support interaction (MSI) and decreased the Ni particle size, resulting in the better glycerol conversion and H2 selectivity, especially for Ni/MA-E catalyst, where the ATP was pretreated using EDTA. In addition, the bimetallic NiFe/MA-E catalyst exhibited the highest conversion of glycerol to gas product (54.4%) and H2 selectivity (84.6%) at very low temperature (280 °C). These results were attributed to the strongest the interplay of active metal with support by the formation of Ni–Fe alloy, resulting in the highest active metal dispersion, smallest metal particle size, lowest the reducibility of active metal and most surface Ni0 content. According to the characterizations of spent catalysts, it demonstrated that monometallic Ni catalysts presented obvious sintering of Ni metal particle and larger accumulation of carbon deposition, which led to the deactivation of the catalyst. While NiFe/MA-E catalyst showed less particle agglomeration and coke formation attributed to the lower content of surface acid site. Apart from that, another cause of catalyst deactivation might be the destruction of ATP skeleton during APRG.

Comparison of gelatinous and calcined magnesia supported Ni or/and Co-based catalysts for aqueous phase reforming of glycerol

In this work, two different types of catalysts with MgO support for aqueous phase reforming of glycerol were prepared by the sol-gel method and calcining method, respectively, and the active metals (nickel or/and cobalt) were added by the initial wet impregnation (IWI) method. It is found that the catalyst supported by gelatinous MgO presents better dispersion and the amount of hydrogen produced by the catalyst containing gelatinous MgO support is more than 1.5 times compared with other catalysts. For the Ni–Co bimetallic catalysts, the higher reaction temperature is beneficial to hydrogen yield, but decreases hydrogen selectivity. A high concentration of glycerol increases hydrogen yield and selectivity. Introducing CaO as an absorbent in aqueous phase reforming can improve WGS reaction and reduce methanation reaction through in-situ CO2 removal and capture. The gelatinous Ni–Co/MgO catalyst presents superior activity and multi-cycle stability.

Lignin Depolymerization and Monomeric Evolution During Fast Pyrolysis Oil Upgrading with Hydrogen from Glycerol Aqueous Phase Reforming

Lignin Depolymerization and Monomeric Evolution During Fast Pyrolysis Oil Upgrading with Hydrogen from Glycerol Aqueous Phase Reforming

Biohydrogen production by glycerol Aqueous-Phase Reforming: Effect of promoters (Ce or Mg) in the NiAl2O4 spinel-derived catalysts

Biohydrogen production by Aqueous-Phase Reforming (APR) of glycerol was studied over nickel aluminate spinel-derived catalysts modified by Ce or Mg. As reference, an alumina supported nickel catalyst was also investigated. Catalysts were characterised by a sort of techniques in order to elucidate any structure-activity relationship, and tested for the WGS and CO hydrogenation reactions. It was concluded that the spinel catalyst allowed a better dispersion of the metallic Ni, and led to a more APR active and more hydrogen-selective catalyst. Mg and Ce doping further increased the nickel dispersion and increased basicity what could be related to their higher WGS relative reaction rate. Also, Mg doping hindered nickel reduction due to Ni-Mg interactions. Both promoters improved the stability of the textural properties under APR conditions, minimizing the formation of boehmite. Leaching of Ni was found, at lesser extent after Mg doping.

Effect of impurities of CH3OH, CH3COOH, and KOH on aqueous phase reforming of glycerol over mesoporous Ni–Cu/CeO2 catalyst

Impurities are inevitable in crude glycerol, a by-product of biodiesel, which has a great influence on aqueous phase reforming (APR). This work investigates three impurities (CH3OH, CH3COOH, and KOH) in the aqueous phase reforming of glycerol (GAPR) using a mesoporous Ni–Cu/CeO2 catalyst at three temperatures. The experiment results indicate that the increase of temperature is beneficial to the conversion of glycerol into gas products, but not favor to the proportion of H2 in the gas phase. The presence of CH3OH almost has not affected the total gas volume, while CH3COOH and KOH decreased and increased the gas volume, respectively. The deactivation of the catalyst occurs under acidic conditions because the active phase Ni on the catalyst surface is lost in the hydrogen evolution reaction. KOH has the greatest influence on the gas phase composition, which greatly increases the H2 production and the proportion of H2. The results of liquid-phase solution analysis show that the addition of CH3COOH promoted the dehydration of glycerol, which is contrary to the results obtained by adding KOH. CH3OH, as the final product of glycerol dehydrogenation and decarbonization, is added to the initial solution, which will be conducive to the dehydration reaction. The addition of CaO can increase the H2 production in the APR of glycerol solution containing impurities.

Aqueous phase reforming of biodiesel byproduct glycerol over mesoporous Ni-Cu/CeO2 for renewable hydrogen production

Aqueous phase reforming (APR), regarded as one method for inexpensive H2 production, was widely studied due to lower temperature and unnecessary to vaporize water and fuels. In this study, the mesoporous CeO2, regarded as a metal oxide carrier, was first prepared by colloidal solution combustion, and then the Ni-Cu bimetallic supported on mesoporous CeO2 was successfully synthesized to investigate the catalytic performance in APR of biodiesel byproduct glycerol. The results show that the Cu element in the catalysts can effectively improve water–gas shift (WGS) reaction and inhibit the formation of methane, which increases the H2 production rate from 125.08 to 195.57 µmol⋅min−1⋅g cat−1. The higher reaction temperature is beneficial to the H2 production rate, but not to H2 selectivity. Kinetics analysis indicates that catalyst of 1Ni2Cu/CeO2 + 0.2gCaO has the lowest apparent activation energy (29.86 kJ⋅mol−1). CaO is introduced as an absorbent to improve WGS reaction and reduce methanation reactions through in-situ CO2 removal and capture. The reaction path and mechanism of APR of glycerol are also discussed in this paper.

In-situ hydrogenolysis of glycerol using hydrogen produced via aqueous phase reforming of glycerol over sonochemically synthesized nickel-based nano-catalyst

1,3-Propanediol (1,3-PDO) is a commercially valuable chemical for the production of polytrimethylene terephthalate polymers and polyurethane. In this study, the production of 1,3-PDO was investigated via aqueous phase reforming (APR) and selective hydrogenolysis of glycerol over Ni-Ca/CeO2 catalysts synthesized by sonochemical (Us) and wet impregnation (WI) methods. The experiments were performed in a batch reactor at 20 bar, 230 ℃, and 450 rpm for 1 h. The synthesized catalysts were characterized using XRD, TEM, FESEM, BET, H2-TPR, XPS, CO-chemisorption, and NH3-TPD to better understand the physio-chemical and surface characteristics. The results revealed that sonochemical catalysts showed a larger surface area, smaller crystallite size, low reduction temperature and more homogenous particle distribution than wet impregnation catalysts. For both preparation methods, monometallic Ni/CeO2 catalysts showed the highest activity, whereas Ca modification of Ni/CeO2 catalysts significantly decreased the activity of the catalysts. The highest yield and selectivity of 1,3-PDO were 19.54% and 52.73%, respectively, using Ni/CeO2_Us catalyst. The best catalyst was further utilized for parameters optimization study to observe the effect of varying glycerol concentration (10 to 25 vol.%), temperature (210 to 250 ℃) and pressure (10 to 30 bar) on the yield and selectivity of 1,3-PDO and glycerol conversion. The results demonstrated that the highest yield (19.54%) and selectivity (52.73%) of 1,3-PDO were obtained over 10 vol.%, 230 ℃ and 20 bar with glycerol conversion of 54.26%. This present study provides a promising and economical process of converting glycerol to 1,3-PDO, which has wide applications in the industry.