Reforming Of Glycerol Research Articles

Isothermal CO2 separation Enabled by redox-active mixed oxide sorbents

This study reports an isothermal CO2 capture strategy using redox-active perovskite oxides and demonstrates its application in sorption-enhanced hydrogen production. Using a thermodynamic analysis, we investigated the relationship between the equilibrium oxygen partial pressure and the extent of CO2 sorption as well as the theoretical hydrogen purity. To validate the concept, calcium and cobalt co-doped SrFeO3 (SrxCa1-xFeyCo1-yO3-δ) samples were screened experimentally to assess their (isothermal) CO2 sorption capacity and reducibility. The optimal sorbent, Sr0.6Ca0.4Fe0.7Co0.3O3-δ (SCFC-6473), underwent further characterizations and was used for isothermal sorption-enhanced steam reforming (iSESR) of glycerol to produce H2, achieving 93 vol% H2 purity. In addition, we present iSESR of biogas and isothermal sorption-enhanced gasification (iSEG) of pulverized pine by Sr0.875Ba0.125MnO3-δ (SBM 718) to validate the generalizability of the proposed concept for a variety of applications. Nearly 90 % syngas efficiency was demonstrated for iSEG of biomass while producing a hydrogen enriched (73 vol%) syngas product.

Nano based nickel catalyst doped with promoters for renewable hydrogen production via steam reforming of glycerol

Nano based nickel catalyst doped with promoters for renewable hydrogen production via steam reforming of glycerol

Synthesis and characterization of nickel based bimetallic nano catalyst for production of clean hydrogen by steam reforming of glycerol

Synthesis and characterization of nickel based bimetallic nano catalyst for production of clean hydrogen by steam reforming of glycerol

Fabrication and catalytic assessment of Ni/Ce–Zr–O catalyst for enhanced hydrogen production via steam reforming of glycerol

The valorization of glycerol, a plentiful byproduct derived from the biodiesel industry, for green hydrogen production via steam reforming (GSR) has attracted considerable attention. Nevertheless, catalysts developed for GSR encounter critical obstacles related to thermal stability and coke deposition during prolonged operations. In this study, we strategically employed thermally stable ZrO2 as a support along with redox-active Ce as a promoter for Ni to optimize both the preparation method and constituent content of the Ce-promoted Ni/ZrO2 catalyst for GSR. The physicochemical properties of both fresh and GSR-used catalysts were investigated using a range of characterization techniques, including XRD, H2-TPR, SEM-EDS/TEM, N2 adsorption/desorption, and TGA. The results demonstrate that the sol-gel method yields a Ni/Ce–Zr–O catalyst with smaller Ni crystals and a higher surface nickel content compared to the step impregnation and co-precipitation methods, thereby achieving enhanced catalytic activity. Moreover, the catalyst prepared by the sol-gel method exhibited excellent activity stability at elevated feedstock concentrations. Furthermore, it has been determined that there is an optimized amount of Ce doping for the Ni/ZrO2 catalyst, which allows the catalyst to achieve the highest pore parameters and surface nickel content. Among the studied catalysts, the one containing 30/50 wt% of designed CeO2/ZrO2 achieved the highest and most stable H2 yield (4.32 mol⋅mol−1) and carbon gasification efficiency (70.28 %) during a 24-h's GSR with a feedstock concentration of 15 wt% at 500 °C (with a WHSV of 45 h−1). Importantly, this optimized Ni/Ce–Zr–O catalyst effectively eliminates the deposition of filamentous/crystallized coke during long-term GSR operation due to enhanced oxygen vacancies created by the formed CexZr1-xO2 species, making it highly promising for large-scale applications.

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.

Experimental investigation for in-situ hydrogen production by electrochemical reforming of glycerol

In this paper, hydrogen production from glycerol have been investigated in a cubic electrolysis cell with/without membrane and in the system with membrane electrode assembly (MEA). Membrane and electrode effects on hydrogen production were examined in the electrolysis cell originally designed and manufactured. A constant current density value of about 10 mA/cm2 was recorded in the electrochemical reforming of glycerol in acidic electrolyte conditions in the system using Nafion 117 membrane at room temperature under 2 V constant potential. The highest current density value was reached in the case where the oxidation of glycerol at the anode occurred on the Zn electrode and the hydrogen evolution reaction at the cathode occurred on the Pt electrode. The current density value increased by 24 % using a Pt electrode instead of Zn at the cathode. According to the results of the cathode peak area in the gas chromatography analysis, the highest hydrogen formation was recorded under these conditions. To create MEA, 5.7 mg/cm2 10 % Pt/C (0.57 mg/cm2 Pt) and 5 mg/cm2 Zn were loaded for the cathode and anode respectively. A nozzle-type current collector made of copper material was selected among the current collectors of different geometries and materials used in the electrochemical reforming of glycerol. A constant current density value of approximate 500 mA/cm2 was achieved under the specified conditions and with diverse system improvements.

Ni Nanoparticles Supported on CeO2 as Catalysts for Aqueous-Phase Glycerol Reforming

Ni Nanoparticles Supported on CeO₂ as Catalysts for Aqueous-Phase Glycerol Reforming

Removal of silica in rice husk derived Ni/biochar modifies reaction intermediates formed and minimizes coking in steam reforming of glycerol

Metal/biochar catalyst features with the advantages for easy recovery of chemical energy of biochar carrier and metal species via simply combustion. Another unique feature of biochar carrier is intrinsic inorganic species, which might also interact with metal species in resulting catalyst. This was investigated herein by synthesis of the Ni/biochar with rice husk-derived biochar carrier pretreated with NaOH for removal of SiO2 and evaluation of the resulting catalysts in steam reforming of glycerol. The solid phase reactions between NaOH and biochar (mass ratio: 2) plus subsequent washing removed 94.6% of ash (mainly SiO2). This formed Ni/biochar of fragmented surface with specific surface area increasing from 207.8 to 457.4 m2g-1 and simultaneously increasing mesopore percentage from 15.5% to 24.0%. NaOH treatment also effectively removed significant portion of both Lewis and Brønsted acidic sites but created abundant alkaline sites. These drastically enhanced nickel dispersion and activity for steam reforming. In-situ IR characterization suggested enhanced adsorption/activation of CO2 and H2O over Ni/biochar treated with NaOH (Ni/biochar-NaOH), which mitigated accumulation of coke precursors bearing CO or CC via accelerated gasification reactions. This led to the reduced amount of coke (mass ratio to catalyst) from 193.4% to 94.7% over Ni/biochar treated with 2-fold of NaOH or to 111.3% over Ni/biochar treated with 1-fold of NaOH. The coke formed was mainly catalytic type in form of carbon nanotube over Ni/biochar-NaOH. The superior resistivity to coking originated from developed pores, enhanced Ni dispersion and abundant alkaline sites from the NaOH treatment.

In-depth analysis of embedded-type structures of NixMg4-xAl LDO-composited catalysts and the impacts on glycerol conversion under a base- and H2-free condition

Core-shell composite catalysts composing of AgO@SnO2/ZSM-5 embedded by NixMg4-xAlO LDOs with various Ni/Mg ratios were characterized and tested for the activity on the conversion of glycerol to valuable chemicals under a base-free and external H2-free condition. As a result, the catalytic performance of an embedded composite was found greater than that of its individual constituents, owing to the synergy between a NixMg4-xAlO lodge and embedded AgO@SnO2/ZSM-5. The highest yield of 1,2-propanediol and lactic acid was achieved at the Ni/Mg ratio of 0.2/3.8. NixMg4-xAlO lodges were found to simultaneously drive glycerol dehydration to acetol and glycerol reforming, driven by Ni sites, forming in-situ H2 that enhances 1,2-propanediol formation whereas the AgO@SnO2/ZSM-5 clusters governed acetol oxidation and Cannizzaro reaction that led to the formation of lactic acid. At a high Ni/Mg ratio, the NixMg4-xAlO lodges completely covered AgO@SnO2/ZSM-5 clusters entirely, resulting in the suppression of lactic acid yield due to over-oxidation.

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.

Insights into Co and Fe-doping effects of mesoporous CeO2 catalysts for dry reforming of glycerol to syngas production

The dry reforming of glycerol (GDR) is one of the alternatives for syngas production by utilizing biodiesel byproduct glycerol and CO2. The development of highly active and stable catalyst is significantly important to achieve GDR process, and the current work provides insights into Co and Fe-doping effects of mesoporous CeO2 (CoFeCe) catalysts synthesized by the colloidal solution combustion method. The prepared catalysts presented the uniform mesoporous structure, the doping of Co and Fe metals resulted in stronger metal-support interaction. The GDR experimental data were compared with the non-stoichiometric thermodynamic equilibrium values. The conversions of glycerol and CO2 were increased with increasing the reaction temperatures due to the endothermic GDR reaction, and the H2/CO produced in syngas was in the range of 0.7–1.4. Due to the improvement of Co and Fe metals in the mesoporous structure of CeO2 catalyst, the 7CoFeCe catalyst exhibited excellent and stable GDR performance and no significant signs of deactivation were observed during 76 h test, and the results indicated that the enhanced interaction and high dispersion of Co and Fe in mesoporous CeO2 catalyst could inhibit carbon formation and promote GDR reaction.

Syngas production from dry reforming of glycerol by the NiO/M-Al2O3 catalysts: Effect of various support promoters and various ZrO2 content

Glycerol dry reforming presents an intriguing approach for converting CO2, a greenhouse gas, and glycerol, a renewable resource, into syngas. This study delves into the impact of introducing 5 wt% of ZrO2, CeO2, La2O3, and Y2O3 to the Al2O3 support. Additionally, the study examines the influence of the optimal metal oxide ratio within the support formula on both structural properties and catalytic performance in the glycerol dry reforming process. To investigate these aspects, various catalyst supports were synthesized using a mechanochemical method. Subsequently, nickel-based catalysts were prepared through a wet impregnation technique. The catalysts underwent comprehensive characterization employing techniques such as XRD, BET, H2-TPR, CO2-TPD, TPO, and FESEM analyses to determine their physicochemical properties. The results demonstrated that the sample enhanced with 5 wt% ZrO2 exhibited remarkable performance metrics. Notably, it achieved a catalytic activity of 85.4% glycerol conversion at 650 ℃, while also displaying better stability and resistance to carbon deposition compared to the unpromoted catalyst throughout a 600 minutes reaction period. These enhanced attributes were attributed to the heightened specific surface area of the support (241.95 m2/gr), the effective dispersion of Ni on the support and the increase in basic sites.

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.

Experimental studies on renewable hydrogen production by steam reforming of glycerol over zirconia promoted on Ni/Al2O3 catalyst

Abstract The impact of ZrO2 as a catalytic promoter for nickel-based alumina supported catalysts has been studied for the hydrogen synthesis via glycerol steam reforming. Hydrogen is a promising contender of clean fuel and has a key significance in the quest of an environment-preservation, low emission and more sustainable energy approach. Glycerol is a by-product produced during production of biodiesel by trans-esterification of vegetable oils. The higher hydrogen content in glycerol makes it the potential renewable feedstock for hydrogen production. Steam reforming process is the best method available which is highest in energy efficiency and most importantly most economical. The production of catalysts was based on the wet impregnation and co-precipitation methods. The majority of the bulk and surface properties of different synthesized catalysts were considered and determined by several characterization techniques like X-ray diffraction technique, BET surface area and scanning electron microscopy. The performance of catalyst is based on glycerol conversion and hydrogen yield obtained from the steam reforming process taking place in the fixed bed catalytic reactor. The effect of different operating conditions like contact time, temperature, metal loading, and steam to glycerol ratio were investigated to produce maximum hydrogen and glycerol conversion. The results show that the incorporation of promoter 2 % ZrO2 improved the activity of Ni/Al2O3 catalysts significantly resulting 96 % glycerol conversion, 84 % hydrogen production and greater stability at contact time = 15 kg cat s/mol, temperature = 800 °C, steam to glycerol ratio = 9:1 mol/mol, and pressure = 1 atm.

Co-reforming of methanol and glycerol with steam: Interaction of the reaction intermediates for aiding gasification of precursors of coke

Glycerol is an important product in manufacturing biodiesel, which could be used as a feedstock for producing hydrogen. However, glycerol and its derived intermediates tends to polymerize under the conditions of steam reforming. In this study, adding methanol as a co-reactant in steam reforming of glycerol with Ni/KIT-6 catalyst for generating oxygen-rich intermediates to tackle forming polymeric coke from glycerol by polymerization reactions. The results indicated that the interaction of the intermediates formed from methanol with the ones from glycerol enhanced the overall reactivity of glycerol towards steam reforming. Adding methanol facilitated forming hydroxyl group and the absorbed *CO2, promoting the gasification of coke precursors like CHx* species. The reaction intermediates with CO or C–O–C functionalities were also suppressed to form, minimizing their polymerization to polymeric coke. Via this, the formation of coke from glycerol or its derived reaction intermediates was effectively suppressed while the catalytic activity was enhanced. In addition, methanol presence led to the formation of mainly the catalytic coke of much higher thermal stability and less aliphatic nature with the morphology of carbon nanotube of thick walls.

Growing hydrogen production by merging the glycerol steam reforming and water gas shift reactions into a single reactor

One promising idea to use excess glycerol generated during biodiesel fabrication is to produce hydrogen (H2) via the steam reforming of glycerol (GSR). This study combined GSR and water-gas shift (WGS) reactors to minimize energy usage and carbon monoxide (CO) emissions while augmenting H2 production. Choice of a Ni/γ-Al2O3 catalyst for the GSR reaction at 0.101 MPa and 923 K resulted in a product stream having 66.12% and 9.68% H2 and CO, respectively. For the WGS reactor, a Pt/HAP catalyst achieved 100% conversion of CO at 0.101 MPa and 723 K. Combining the two catalysts at an optimized temperature of 923 K for over 15 h resulted in H2 and CO levels at 69.85% and 1.77%, respectively: thus, increasing the production rate of H2 by 5% while reducing CO by 81%. Coking did occur during the GSR reaction. Overall, the combined reactor has potential to reduce complexity and energy usage.

Cobalt aluminate spinel-derived catalysts for glycerol steam reforming

Steam reforming of glycerol presents a promising possibility for the production of clean hydrogen. The steam reforming of glycerol (10 wt%) utilizing catalysts derived from cobalt aluminate spinel was examined at 550 °C, while the space–time covered 3.76–37.60 g·h/mol. Among the characterization techniques, glycerol desorption tests (glycerol-TPD) were conducted to assess the feasibility of the catalytic system for dehydration/dehydrogenation activity. The 0.625CoAl catalyst displayed the highest conversion of carbon to gas and selectivity to H2, which corresponds to the higher H2 desorption at lower temperature levels observed in the glycerol-TPD experiments. The catalyst's deactivation and regeneration were studied on 0.25CoAl catalyst under severe operation conditions and resulted in cobalt leaching detection. Raman spectroscopy and temperature programmed oxidation (TPO) revealed the formation of predominantly amorphous carbon on the surface of the catalyst.

Cr and CeO2 promoted Ni/SBA-15 framework for hydrogen production by steam reforming of glycerol.

Ni/SBA-15 meso-structured catalysts modified with chromium and CeO2 (Ni-Cr-CeO2/SBA-15) were utilized to produce hydrogen from glycerol steam reforming (GSR). The catalysts were synthesized by a one-pot hydrothermal process and extensively characterized by analytical techniques such as N2 adsorption-desorption (BET), H2-temperature programmed reduction (H2-TPR), powder X-ray diffraction (PXRD), inductively coupled plasma-optical emission spectrometry (ICP-OES), and transmission electron microscopy (TEM). The low-angle XRD reflections affirmed that the catalysts were crystalline and possessed a 2D-ordered porosity. The BET results depicted that all the catalysts exhibited a good surface area ranging from 633 to 792m2/g, and the pore sizes were consistently in the mesoporous range (between 3 and 5nm). TEM analysis of both calcined and spent catalysts revealed that the metal active sites were embedded in the hybrid CeO2-SiO2 support. Overall, the Ni-based catalysts exhibited higher glycerol conversion -12Ni-SBA-15-99.9%, 12Ni3CeO2-SBA-15-89.4%, and 8Ni4Cr3CeO2-SBA-15-99.7%. Monometallic 12Ni/SBA-15 performed exceptionally well, while 12Cr/SBA-15 performed poorly with the highest 71.48% CO selectivity. For short-term GSR reactions, CeO2 addition to 12Ni/SBA-15 did not have any effect, whereas Cr addition resulted in a 32% decrease in H2 selectivity. The long-term stability studies of 12Ni-SBA-15 showed H2 selectivity of ~ 64% and ~ 98% glycerol conversion. However, its activity was short-lived. After 20-30h, the H2 selectivity and conversion dropped precipitously to 40%. The doping of mesoporous Ni/SBA-15 with Cr and CeO2 remarkably enhanced the long-term stability of the catalyst for 12Ni3CeO2-SBA-15, and 8Ni4Cr3CeO2-SBA-15 catalyst which showed ~ 58% H2 selectivity and ~ 100% conversion for the entire 60h. Interestingly, Cr and CeO2 seem to improve the shelf-life of Ni-SBA-15 via different mechanistic pathways. CeO2 mitigated Ni poisoning through coke oxidation whereas Cr bolstered the catalyst stability via maintaining a well-defined pore size, structural rigidity, and integrity of the heterogeneous framework, thereby restricting structural collapse, and hence retard sintering of the Ni active sites during the long-term 60h of continuous reaction. Hydrogen generation from renewable biomass like glycerol could potentially serve as a sustainable energy source and could substantially help reduce the carbon footprint of the environment.