Glycerol Dry Reforming Research Articles

Production of syngas via glycerol dry reforming on Ni catalysts supported on mesoporous nanocrystalline Al2O3

Mesoporous Ni/γ- Al2O3 catalysts with various Ni contents were synthesized and employed in glycerol dry (CO2) reforming (GDR) reaction. The results revealed that increasing the Ni content from 5 to 20 wt.%, decreased the BET areas of the samples from 180 to 143 m2/g and increased the Ni crystalline size from 6.6 to 19 nm. Moreover, the catalytic activities of different catalysts were studied and the results revealed that 15 wt.% Ni/Al2O3 possessed the maximum catalytic activity. Finally, the stability of the catalyst with maximum activity was investigated for 20 h of reaction at 700 °C. The results showed a significant decline in catalytic activity during the first 5 h of reaction followed with a stable activity for 15 h time on stream.

Synthesis and Application of Noble Metal Nanocatalysts Supported on MgAl2O4 in Glycerol Dry Reforming Reaction

Noble metal catalysts (Rh, Ru, Ir, Pd, Pt) supported on alumina-stabilized magnesia (MgAl2O4) were prepared and employed in order to convert glycerol to syngas in the presence of carbon dioxide. The physiochemical properties of the fresh and spent catalysts were determined using BET, TPR, TPO, TEM and H2S chemisorption techniques. The BET analysis showed higher surface area for the Rh, Ru and Pd catalysts compared to other samples. The TEM images of the prepared catalysts exhibited that the sizes of the active metals are smaller than 5 nm with high dispersion on the surface of the catalyst carrier. The H2S chemisorption results showed that the crystallite sizes of the noble metals were in the range of 1.28–4.2 nm. The catalytic results showed that the Rh catalyst exhibited the highest activity and stability in this reaction. The high activity of Rh catalyst could be attributed to its high BET and active metal areas. The catalytic activity of Rh catalyst declined with time on stream due to the carbon formation. It was seen that increasing the CO2 to glycerol ratio (CGR) from 0 to 3 improved the catalytic activity and decreased the amount of deposited carbon on the catalyst surface. The noble metal nanocatalysts were prepared and employed for the production of synthesis gas via glycerol dry reforming. Rh nanocatalyst exhibited the highest catalytic activity in this reaction.

Characterization of Ag-promoted Ni/SiO2 Catalysts for Syngas Production via Carbon Dioxide (CO2) Dry Reforming of Glycerol

The carbon dioxide (CO2) dry reforming of glycerol for syngas production is one of the promising ways to benefit the oversupply crisis of glycerol worldwide. It is an attractive process as it converts carbon dioxide, a greenhouse gas into a synthesis gas and simultaneously removed from the carbon biosphere cycle. In this study, the glycerol dry reforming was carried out using Silver (Ag) promoted Nickel (Ni) based catalysts supported on silicon oxide (SiO2) i.e. Ag-Ni/SiO2. The catalysts were prepared through wet impregnation method and characterized by using Brunauer-Emmett-Teller (BET) surface area, Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Thermo Gravimetric (TGA) analysis. The experiment was conducted in a tubular reactor which condition fixed at 973 K and CO2:glycerol molar ratio of 1, under atmospheric pressure. It was found that the main gaseous products are H₂, CO and CH4 with H₂:CO molar ratio < 1.0. From the reaction study, Ag(5)-Ni/SiO2 results in highest glycerol conversion and hydrogen yield, accounted for 32.6% and 27.4%, respectively.

CO2 reforming of glycerol over La-Ni/Al2O3 catalyst: A longevity evaluative study

This paper reports on the longevity of glycerol-dry (CO2) reforming over the lanthanum (La) promoted Ni/Al2O3 catalysts. The XRD results showed that the Ni particle was well-dispersed in the presence of La promoter. In addition, via the NH3-TPD analysis, it was found that the La promoter has reduced the acidity of Ni catalyst which may have explained the mitigation of carbon laydown. It was determined that the 3.0 wt% La-promoted Ni/Al2O3 catalyst possessed the largest BET specific surface area of 97 m2·g−1. Consequently, it yielded the best catalytic longevity performance with conversion attained more than 90%, even after 72 h of reaction duration. Significantly, it can be confirmed that the presence of CO2 during the glycerol dry reforming was essential in reducing carbon deposition, most likely via gasification pathway. This has ensured a stability of catalytic activity for a long reaction period (72 h).

Syngas production from glycerol-dry(CO2) reforming over La-promoted Ni/Al2O3 catalyst

A 3 wt% La-promoted Ni/Al2O3 catalyst was prepared via wet co-impregnation technique and physicochemically-characterized. Lanthanum was responsible for better metal dispersion; hence higher BET specific surface area (96.0 m2 g−1) as compared to the unpromoted Ni/Al2O3 catalyst (85.0 m2 g−1). In addition, the La-promoted catalyst possessed finer crystallite size (9.1 nm) whilst the unpromoted catalyst measured 12.8 nm. Subsequently, glycerol dry reforming was performed at atmospheric pressure and temperatures ranging from 923 to 1123 K employing CO2-to-glycerol ratio from zero to five. Significantly, the reaction results have yielded syngas as main gaseous products with H2:CO ratios always below than 2.0 with concomitant maximum 96% glycerol conversion obtained at the CO2-to-glycerol ratio of 1.67. In addition, the glycerol consumption rate can be adequately captured using power law modelling with the order of reactions equal 0.72 and 0.14 with respect to glycerol and CO2 whilst the activation energy was 35.0 kJ mol−1. A 72 h longevity run moreover revealed that the catalyst gave a stable catalytic performance.

Synthesis and characterisation of cement clinker-supported nickel catalyst for glycerol dry reforming

Glycerol dry reforming was performed in a packed-bed reactor containing 20 wt.% nickel catalyst employing CO2-to-C3H8O3 feed ratios of 0.6 ⩽ CGR ⩽ 5.0 and reaction temperatures between 923 and 1023 K for syngas (H2 and CO) production studies. Liquid N2 physisorption revealed a significant 32-fold increase in the Brunauer–Emmett–Teller (BET) specific surface area upon the incorporation of nickel metal onto the cement clinker support, which was also corroborated by field emission scanning electron microscopy (FESEM). In addition, NH3- and CO2-temperature programmed desorption (TPD) analyses exhibited the presence of a strong pair of acid (1061.4 μmol gcat−1) and basic (1.53 × 104 μmol gcat−1) sites on the catalyst. A bunsenite (NiO) species with a crystallite size of 15–18 nm and calcium silicate were successfully identified from the X-ray diffraction (XRD) pattern. Subsequently, the results appraised from the reaction studies confirmed the absence of a direct interaction between CO2 and the glycerol compound during the glycerol dry reforming and that the H2 was primarily produced from the glycerol decomposition. This finding could be ascribed to the chemisorption of both compounds at different active sites, which resulted in glycerol decomposition as the primary reaction pathway. The optimum condition for H2 production via glycerol dry reforming was at a carbon dioxide-to-glycerol ratio (CGR) of unity (at constant Pgly = 14 kPa) and 973 K. Moreover, the glycerol conversion ranged from 70% to 80% at a CGR of 1–1.67. Glycerol dry reforming was discovered to be more feasible for Fischer Tropsch synthesis, as the H2:CO product ratios were <2.0. The post-characterisation of the used catalysts confirmed the presence of whisker-type carbon, which fortunately can be easily removed via oxidation with O2.

Production of CO-rich hydrogen gas from glycerol dry reforming over La-promoted Ni/Al2O3 catalyst

Dry reforming of glycerol has been carried out over alumina-supported Ni catalyst promoted with lanthanum. The catalysts were characterized using EDX, liquid N2 adsorption, XRD technique as well as temperature-programmed reduction. Significantly, catalytic glycerol dry reforming under atmospheric pressure and at reaction temperature of 1023 K employing 3 wt%La–Ni/Al2O3 catalyst yielded H2, CO and CH4 as main gaseous products with H2:CO < 2.0. Post-reaction, XRD analysis of used catalysts showed carbon deposition during glycerol dry reforming. Consequently, BET surface area measurement for used catalysts yielded 10–21% area reduction. Temperature-programmed gasification studies with O2 as a gasification agent has revealed that La promotion managed to reduce carbon laydown (up to 20% improvement). In comparison, the unpromoted Ni/Al2O3 catalyst exhibited the highest carbon deposition (circa 33.0 wt%).

Application of Cement Clinker as Ni-Catalyst Support for Glycerol Dry Reforming

The increase in biodiesel production inevitably yield plethora of glycerol. Therefore, glycerol has been touted as the most promising source for bio-syngas (mixture of H2 and CO) production. Significantly, coking on nickel-based catalysts has been identified as a major deactivation factor in reforming technology. Indeed, coke-resistant catalyst development is essential to enhance syngas production. The current work develops cement clinker (comprised of 62.0% calcium oxide)-supported nickel catalyst (with metal loadings of 5, 10, 15 and 20 wt%) for glycerol dry reforming (CO2). Physicochemical characterization of the catalysts was performed using XRD, XRF, BET, TGA and FESEM-EDS techniques. Subsequently, reaction studies were conducted in a 7-mm ID fixed-bed stainless steel reactor at 1023 K with various CO2 partial pressures at constant weight-hourly space velocity (WHSV) of 7.2×104 ml gcat-1 h-1. Gas compositions were determined using Agilent 3000 micro-gas chromatography (GC) and Lancom III gas analyzer. Results obtained showed an increment of BET surface area up to 32-fold with Ni loading which was corroborated by FESEM images. Syngas (H2 and CO) ratios of less than 2 were being produced at 1023 K. A closer scrutiny to the transient profile revealed that the presence of CO2 higher or lower than CGR 1:1 promotes the Boudouard reaction. © 2013 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0)

Thermodynamic analysis of glycerol dry reforming for hydrogen and synthesis gas production

A thermodynamic analysis of glycerol dry reforming has been performed by the Gibbs free energy minimization method as a function of CO 2 to glycerol ratio, temperature, and pressure. Hydrogen and synthesis gas can be produced by the glycerol dry reforming. The carbon neutral glycerol reforming with greenhouse gas CO 2 could convert CO 2 into synthesis gas or high value-added inner carbon. Atmospheric pressure is preferable for this system and glycerol conversion keeps 100%. Various of H 2/CO ratios can be generated from a flexible operational range. Optimized conditions for hydrogen production are temperatures over 975 K and CO 2 to glycerol ratios of 0–1. With a temperature of 1000 K and CO 2 to glycerol ratio of 1, the production of synthesis gas reaches a maximum, e.g., 6.4 mol of synthesis gas (H 2/CO = 1:1) can be produced per mole of glycerol with CO 2 conversion of 33%.