Catalytic steam reforming of glycerol over cerium and palladium-based catalysts for hydrogen production

In this work, catalytic steam reforming of glycerol for hydrogen production was performed over Ce/Al2O3 and Pd/Al2O3 catalysts prepared via the impregnation method. The catalysts were characterized by scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM), BET surface area, and X-ray diffraction (XRD). Two sets of catalytic reactions were conducted, one comparing 1% Pd/Al2O3 to 1% Ce/Al2O3 and the second comparing 1% Ce/Al2O3 loading to 10% Ce/Al2O3 loading. All catalytic reactions were performed using a fixed-bed reactor operated at 600 °C and atmospheric pressure. Aglycerol–water mixture at a molar ratio of 1:6 was fed to the reactor at 0.05 ml/min. In the first set of experiments, Pd/Al2O3 exhibited higher hydrogen productivity than Ce/Al2O3. A maximum hydrogen yield of 56% and a maximum selectivity of 78.7% were achieved over the Pd/Al2O3 catalyst. For the second set of experiments, the results show that the reaction conversion increased as the cerium loading increased from 1% to 10%. A total average hydrogen yield of 28.0% and a selectivity of 45.5% were obtained over 1% Ce/Al2O3, while the total average hydrogen yield and selectivity were 42.2% and 52.7%, respectively, for 10% Ce/Al2O3

Steam Reforming of Glycerol over Ni Supported Alumina Xerogel for Hydrogen Production

AbstractMomentous amount of glycerol is produced as a by-product during bio-diesel production by the transesterification of vegetable oils, which are available at low cost in large supply from renewable raw materials. As hydrogen is a clean energy carrier, conversion of glycerol to hydrogen is one among the most attractive ways to make use of glycerol. In this study, the catalytic production of hydrogen by steam reforming of glycerol has been experimentally performed in a fixed-bed reactor. The performance of this process was evaluated over 10wt% Ni supported alumina xerogel catalysts. Ni is impregnated over alumina xerogel which was pretreated at different temperatures of 700°C, 800°C, 900°C and 1000°C. For a comparative purpose, the steam reforming experiments were conducted under same operating conditions, i.e., reaction temperature of 600°C, atmospheric pressure and 1:6 glycerol to water molar ratio where we are getting 100% glycerol conversion in all the runs. The results showed that the hydrogen production increased with the increase in the treatment temperature of the support. The highest amount of hydrogen produced was attained over 10wt% Ni doped alumina xerogel pretreated at 1000°C. The catalytic enhancement over the best catalyst system is due to the thermal stability of the support which is treated at highest temperature. Sol gel method of preparation is implemented in the support development and different catalyst systems used in the reforming process were characterized using X-ray powder diffraction, BET surface area and SEM analysis

The Activity of Ni-Based Catalysts on Steam Reforming of Glycerol for Hydrogen Production

Glycerol, the readily available bio renewable material, is effectively utilized for hydrogen production by a steam reforming reaction. The experiments were carried out in a continuous flow fixed-bed reactor over Nickel supported alumina catalysts under atmospheric pressure at 600°C and three hours reaction time. 5%wt Ni was loaded over γ-Al2O3 and effect of promoter metals such as Fe and Co over Ni/γ-Al2O3 catalytic systems were evaluated. The catalysts were characterized by BET surface area, XRD and SEM techniques. The activity results showed that the addition of Co enhanced the catalyst performance. The catalysts exhibited a good activity and selectivity to hydrogen

Sucrose helps regulate cold acclimation of Arabidopsis thaliana

A test was carried out to see if sucrose could regulate cold-acclimation-associated gene expression in Arabidopsis. In plants and excised leaves, sucrose caused an increase in GUS activity, as a reporter for the activity of the cold-responsive COR78 promoter. This increase was transient at 21 °C but lasted for at least 4 d at 4 °C in continuous darkness. However, at 4 °C with a 16 h photoperiod, GUS activity was similarly high with solutions lacking sucrose or with different concentrations of sucrose. In peeled lower epidermis in the cold dark environment, 40 mM sucrose increased COR78 transcript abundance to substantially above that in the controls, but sorbitol had no effect. Similarly to the cold and dark conditions, sucrose increased COR78 transcript abundance in the epidermis in the warm light and warm dark environments, but not in a cold light environment. Sucrose had much less effect on COR78 transcript abundance in leaves without the lower epidermis. Thus sucrose regulates expression of COR78, possibly mainly in the epidermis, at the level of transcription. Furthermore, 40 mM sucrose at 4 °C for 24 h in constant darkness was sufficient to give the same GUS activity as in fully acclimated plants of the same age in a 16 h photoperiod, although by 48 h, GUS activity had become intermediate between control and fully cold-acclimated plants. Thus sucrose has a regulatory role in the acclimation of whole plants to cold and this may be important during diurnal dark periods

Understanding signalling in acclimation to cold stress

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Investigation of the process conditions for hydrogen production by steam reforming of glycerol over Ni/Al2O3 catalyst using response surface methodology (RSM)

In this work; a response surface methodology (RSM) was implemented to investigate the process variables in a hydrogen production system. The effects of five independent variables; namely the temperature (X1); the flow rate (X2); the catalyst weight (X3); the catalyst loading (X4) and the glycerol-water molar ratio (X5) on the H2 yield (Y1) and the conversion of glycerol to gaseous products (Y2) were explored. Using multiple regression analysis; the experimental results of the H2 yield and the glycerol conversion to gases were fit to quadratic polynomial models. The proposed mathematical models have correlated the dependent factors well within the limits that were being examined. The best values of the process variables were a temperature of approximately 600 °C; a feed flow rate of 0.05 mL/min; a catalyst weight of 0.2 g; a catalyst loading of 20% and a glycerol-water molar ratio of approximately 12; where the H2 yield was predicted to be 57.6% and the conversion of glycerol was predicted to be 75%. To validate the proposed models; statistical analysis using a two-sample t-test was performed; and the results showed that the models could predict the responses satisfactorily within the limits of the variables that were studied

Hydrogen Production by Steam Reforming of Ethanol over Nickel Catalysts Supported on Sol Gel Made Alumina: Influence of Calcination Temperature on Supports

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