Agus Haryanto

Co-gasification of hardwood chips and crude glycerol in a pilot scale downdraft gasifier.

Seeking appropriate approaches to utilize the crude glycerol produced in biodiesel production is very important for the economic viability and environmental impacts of biodiesel industry. Gasification may be one of options for addressing this issue. Co-gasification of hardwood chips blending with crude glycerol in various loading levels was undertaken in the study involving a pilot scale fixed-bed downdraft gasifier. The results indicated that crude glycerol loading levels affected the gasifiers performance and the quality of syngas produced. When crude glycerol loading level increased, the CO, CH(4), and tar concentrations of the syngas also increased but particle concentration decreased. Though further testing is suggested, downdraft gasifiers could be run well with hardwood chips blending with liquid crude glycerol up to 20 (wt%). The syngas produced had relatively good quality for fueling internal combustion engines. This study provides a considerable way to utilize crude glycerol.

Glycerin steam reforming for hydrogen production.

Biodiesel production is expected to grow steadily in the future. In converting vegetable oils into biodiesel, approximately 10% (w/w) of glycerin is produced as a by-product. With the increasing production of biodiesel, there would be glut of glycerin in the world market; therefore, it is essential to find useful applications for this by-product. Glycerin is a potential feedstock for hydrogen production because one mole of glycerin can produce up to four moles of hydrogen. The objective of this study was to develop, test, and characterize promising catalysts for hydrogen production from steam reforming of glycerin. The following five catalysts were prepared on ceramic foam monoliths (92% Al2O3, 8% SiO2): rhodium-cerium, rhodium-cerium-platinum, ruthenium-yttrium, nickel, and iridium. The catalysts were prepared by the incipient wetness technique. This article discusses selectivity data of the selected gases resulting from the glycerin steam reforming process. The study found that the rhodium-cerium-platinum catalyst was the most selective towards hydrogen under the experimental conditions investigated (700°C, 1 atm, and gas hourly specific velocity of 9.2 × 104 h-1). The glycerin conversion was 100% with all the catalysts tested.

Catalytic Biomass Gasification to Produce Sustainable Hydrogen

Hydrogen is believed to be the future energy carrier because it produces power with no environmentally harmful emissions. However, current hydrogen production mainly use steam reforming of fossil fuels such as natural gas, oil, naphtha, and coal in which carbon dioxide ( CO2) as a byproduct is unavoidable. Alternatively, biomass gasification is an environmentally friendly way to produce hydrogen since it contributes zero net CO2 emissions. However, using conventional gasification processes results in relatively low hydrogen yields, increasing hydrogen composition in the flue gas of biomass gasification is of interest. Coupling a secondary reactor for water gas shift reaction downstream is commonly used for this purpose. However, the reaction needs an active catalyst. This paper discusses some catalysts that could be used to increase hydrogen composition through water gas shift reaction in biomass gasification. The promising catalysts include dolomite, nickel, and noble metal based catalysts.

Biogas production from anaerobic codigestion of cowdung and elephant grass (Pennisetum Purpureum) using batch digester

This study aimed at determining biogas production from codigestion of Elephant grass and cowdung using batch digester. Fresh grass was manually chopped with a maximum length of 3 cm. Chopped grass (25 kg) was perfectly mixed with fresh cowdung (25 kg). The mixture was introduced into a 220-liter batch drum digester. The substrate was diluted with water at different rates (P1 = 50 L, P2 = 75 L, and P3 = 100 L) and was stirred thoroughly. Six digesters were prepared as duplicate for each treatment. Two other digesters containing only 25 kg cowdung diluted with 25 L water were also provided as control treatment (P0). The digesters were air tightly sealed for 70 days. Observation was conducted on daily temperature, substrate pH (initial and final), TS and VS content, biogas yield and biogas composition. Results showed that final pH of grass containing substrate was in the acidic range, namely 4.50, 4.62, 6.82, whereas that of control (P0) was normal with pH of 7.30. Digester with substrate composition 25:25:100 (cowdung:grass:water) produced the highest biogas total (524.3 L). Biogas yield of codigestion, however, was much lower as compared to that of control, namely 7.35, 16.75, and 111.72 L/kg VS r respectively for treatment P1, P2, P3. with dilution rate of 50, 75, and 100 L. Biogas produced from control digester had methane content of 53.88%. In contrast, biogas resulted from all treatments contained low methane (the highest was 31.37%). Methane yield of 39.3 L/kg TS removal was achieved from digester with dilution 100 L (P3). Mechanical pretreatment is suggested to break Elephant grass down into smaller particles prior to introducing it into the digestion process.

Crude Glycerol Co-gasification with Hardwood Chips in a Pilot-Scale Downdraft Gasifier

With increasing production of biodiesel, a glut of glycerol (C3H8O3) is expected in the world market. The market will likely to be saturated because of limited utilization of glycerol in the world. As a result, the price of glycerol decreases dramatically. Therefore, it is essential to find other useful applications for glycerol to improve the economic viability of biodiesel production. One possibility is using glycerol as an additive in the gasification of biomass. Essentially the co-gasification of crude glycerol with hardwood chips was undertaken in this study involving a pilot-scale downdraft gasifier. The effect of glycerol addition to the wood chips (0 to 20%) on the gasification performance was evaluated. The results revealed that addition of crude glycerol up to 10% (wt/wt) was technically possible with the benefit of simple substitution of glycerol for wood chips on a mass basis.

Effects of Feedstock Properties on the Performance of A Downdraft Gasifier

Physicochemical properties of biomass feedstocks, such as composition, shape, size, moisture content, etc., have profound effects on the gasification process. The properties affect feedstock selection, sizing, transportation, and storage; gasification and syngas recovery, and residue or co-product processing. The extent of the effects of feedstock properties depend on gasfier type, operating conditions, and syngas quality product requirements. Fixed-bed downdraft gasifiers are widely used in small-scale biomass gasification facilities because of their simple and robust construction, easy and reliable operation, suitability with various feedstocks, high conversion rate, and production of relatively clean syngas containing low tar and particulate concentrations. A series of gasification tests using different biomass feedstocks, including hardwood chips, softwood chips, softwood sawdust, corn cubes, crude glycerol (a byproduct of biodiesel production), and switchgrass, were conducted under similar operating conditions using a pilot scale fixed-bed downdraft gasifier. The results show that downdraft gasifier is suitable for gasifying diverse feedstocks to produce good quality syngas with good low heating value and low tar and particle concentrations. There are no significant differences in gas composition, low-heating value, tar and particle concentrations among the different feedstocks used in the experiments. The syngas produced by the gasification process can be directly be used as fuel in internal combustion engines (ICE), however the physicochemical properties of feedstock such as shape, size, porosity, and the chemical contents, was found to affect the performance of the fixed-bed downdraft gasifier. Feedstocks with small sizes, low porosity, or containing highly compounds that can caramelize in high temperature could cause problems with bridging, lumping, collapsing, or clogging inside the reaction chamber and could cause the gasifier to fail. Hardwood chips mixed with 20% of liquid crude glycerol can be gasified well in the downdraft gasifier and produced syngas with significant higher CH4 content, good low-heating value and lower tar concentration than those of regular hardwood chips.

Producing Hydrogen through Water Gas Shift Reaction over Nickel Catalysts

Water gas shift (WGS) reaction has an important role in the hydrogen production and related processes such as methanol synthesis, ammonia synthesis, and fuel cell applications. The paper presents the recent advances of WGS process using supported nickel catalysts. The effects of different supports, nickel loading, and reaction temperatures on the catalyst activity and selectivity are discussed. Ceria promoted nickel catalyst supported on powder alumina (Ni/CeO2-Al2O3) demonstrated the best performance. The catalyst was stable at high temperature (450oC) but deactivated at low temperature (250oC). Increasing nickel loading resulted in a better performing Ni/CeO2-Al2O3 catalyst. The activity of 4%Ni/CeO2-Al2O3 was 49% with H2 yield and H2 selectivity were 36% and 61%, respectively.

Thermodynamic Analysis of Increasing Hydrogen Yield of Syngas Produced from Biomass Gasification

Biomass gasification is an environmentally friendly means to produce hydrogen since it has zero net CO2 emissions. Syngas produced is composed of H2, CO, CO2, CH4, trace of higher hydrocarbons (C2H6, C2H4, and C2H2), and tar. Hydrogen yield in the syngas produced from non-catalytic biomass gasification is relatively low. The hydrogen fraction, however, can be increased by converting CO, CH4, higher hydrocarbons, and tar in a secondary reactor downstream. On the other hand, the compositions of the syngas will determine the optimum yield of the process under certain conditions. This paper discusses thermodynamic limits of the synthesis gas upgrading process by employing minimization Gibbs free energy function method. The analysis is performed under temperature ranges of 400 to 1300 °K, pressure of 1 to 10 atm (0.1 to 1 MPa), and different carbon to steam ratios. The results are compared to the experimental data found from literature.

Valuable Products of Glycerin Gasification under Sub- and Supercritical Water Treatment

With increasing production of biodiesel, a glut of glycerin (C3H8O3) is expected in the world market. The market will likely to be saturated because of limited utilization of glycerin in the world. Therefore, it is essential to find other useful applications for glycerin. One possibility is utilization of glycerin as a source of producing chemicals and energy. The paper discusses the possible useful chemicals derived from glycerin through sub- and supercritical water reaction.

Hydrogen Production from Renewable Alcohols over Pt and Ni Catalysts

Recently, biomass resources have attracted considerable attention as an energy source because they are renewable and carbon dioxide neutral. Alcohols that are derived from biomass are perceived as an alternative for hydrogen production. Efficient systems of producing hydrogen are greatly desired. Without catalysts, economical production of hydrogen is impossible and the selection of highly active catalyst(s) is vital. Significant work has been done to understand the decomposition of methanol using various metals for hydrogen production. This paper discusses the activity of two catalysts, Ni (1 1 1) and Pt (1 1 1), for hydrogen production from methanol based on the literature. Results are based on density functional theory calculations. Also, our results obtained using DMol3 are discussed. Analysis using DMol3 is on-going and only a part of the results are presented. We are continuing our analysis for glycerin decomposition. Studies have shown that O-H bond scission is a feasible pathway in case of Ni (1 1 1); whereas both O-H and C-H bond scissions are feasible pathways in Pt (1 1 1). Our study also found that activation energy from O-H bond scission is much lower than C-O bond scission.