Dry Ash-free Basis Research Articles

Catalytic effect of metal salts on deoxygenation and aromatization reaction during pressurized pyrolysis of corncob waste at mild temperatures

Converting biomass to high quality bio-char with high carbon solidification at low energy consumption can greatly promote the application of biomass to alternative coal. Metal salts have been confirmed to enhance carbonization and dehydration during traditional pyrolysis and hydrothermal conversion, whereas the catalytic deoxygenation and aromatization mechanisms during dry mild pyrolysis in the presence of pressure are currently unclear. A mild gas-pressurized pyrolysis assisted by metal salts catalysts at 200–300 °C was proposed in this work. The effects of catalysts on three-phase products as well as synergistic catalytic reaction mechanism were studied. Results indicated that CaCl2, ZnCl2 promoted carbon fixation rates by 19.77 % and 26.89 %, and ZnCl2, KCl could remove oxygen content by 11.45 % and 6.56 % (wt.%, dry ash free basis). ZnCl2 exhibited the best deoxygenation and aromatization effect. With ZnCl2 catalysis at 280 °C, the volatile content reduced to 37.25 %, and O/C, H/C values decreased by 19.05 % and 11.25 %, achieving coking coal-like quality. FTIR and NMR results implied that oxygen-containing functional groups were removed even more rapidly under the catalysis of ZnCl2, facilitating the rearrangement of O-alkyl C and aliphatic C into aromatic C, exhibiting a higher aromatization degree in semi-char. Moreover, CH4 and H2 increased in gas products catalyzed by ZnCl2, while C2H4 and C2H6 decreased. Pressure inhibited the escape of small molecule gas volatiles, making them easily adsorbed on surfaces of molecular structures for secondary reactions. Under the action of the [ZnOZn]2+ acid sites, alkanes underwent dehydrogenation activation to yield H2, and demethylation activation to generate CH4, followed by cyclization reaction. The upgrading promotions of biomass were caused by the synergistic effect of pressure and ZnCl2 catalysis.

Maceral composition, coal quality and depositional environments of the middle Permian Ukhaakhudag coal deposit, South Mongolia

The Ukhaakhudag coal deposit is located c. 560 km SSE of the city of Ulaanbaatar in the northeastern sector the South Gobi Basin. The coal-bearing strata is part of the middle Permian Tavantolgoi Formation. This study aims to determine the coal petrographic composition and depositional environments of five coal seams in the lower part of the deposit based on petrographic and chemical analyses of 106 composite samples. Vitrinite ranges from 12 to 64 vol.%, and inertinite varies between 9 and 68 vol.%. Liptinite ranges from 1 to 7 vol.%. Microlithotype analyses indicate that coals are primarily vitrinertite, few coals are classified as trimaceralic microlithotypes duroclarite and clarodurite. The inorganic fraction in the studied coals is mainly composed of clay, small amounts of silica, carbonate, and pyrite minerals. The vitrinite random reflectance values of the samples vary between 0.93-1.16 %. Volatile matter content varies from 26.10 to 41.48 wt.% (dry ash free basis). Ash, moisture, and sulfur contents vary between 11.20-44.76 wt.%, 1.63-6.03 wt.% and 0.49-1.67 wt.%, (air dried basis) respectively. Based on random vitrinite reflectance values and volatile matter content, the studied coals are classified as coking (Ch4), fat (Ch5), 1/3 coking (Ch6), gas fat (Ch7) based on the Mongolian system and medium to high volatile bituminous coal when using the ASTM system. The Gelification Index and Tissue Preservation Index of the studied samples suggest most seams accumulated in wet forest swamps with a high tree density. The Middle Permian peats from this location accumulated in mostly alternate oxic and anoxic mire conditions. The climate was drier during the peat accumulation of Seam 0, but it became warmer, and humidity increased starting from Seam 3 accumulation.

The geological factors affecting gas content and permeability of coal seam and reservoir characteristics in Wenjiaba block, Guizhou province

The gas content and permeability of coal reservoirs are the main factors affecting the productivity of coalbed methane. To explore the law of gas content and permeability of coal reservoirs in the Zhijin area of Guizhou, taking No.16, No.27 and No.30 coal seams in Wenjiaba mining area of Guizhou as the engineering background, based on the relevant data of coalbed methane exploration in Wenjiaba block, the geological structure, coal seam thickness, coal quality characteristics,coal seam gas content and permeability of the area were studied utilizing geological exploration, analysis of coal components and methane adsorption test. The results show that the average thickness of coal seams in this area is between 1.32 and 1.85 m; the average buried depth of the coal seam is in the range of 301.3–384.2 m; the gas content of No.16 and No.27 coal seams is higher in the syncline core. The gas content of the No.30 coal seam forms a gas-rich center in the south of the mining area. The buried depth and gas content of coal seams in the study area show a strong positive correlation. Under the same pressure conditions, the adsorption capacity of dry ash-free basis is significantly higher than that of air-dried coal. The permeability decreases exponentially with the horizontal maximum principal stress and the horizontal minimum principal stress. The horizontal maximum primary stress and the flat minimum prominent stress increase with the increase of the buried depth of the coal seam. The permeability and coal seam burial depth decrease exponentially. This work can provide engineering reference and theoretical support for selecting high-yield target areas for CBM enrichment in the block.

Facile elimination of alkali and alkaline earth metals from marine biomass-derived carbon for comparative analysis of chemical composition with standard coal and coke

Pyrolysis of marine biomass (MB) to create marine biomass-derived carbon materials (MBCs) for industry is a sustainable solution. In this study, we systematically examined pyrolysis processes and performed elemental composition analyses of MB and MBC. The results revealed that MBC contained 12.5–25.5 mass% of alkali and alkaline earth metals (AAEMs). As the pyrolysis temperature increased, some of these AAEMs underwent physical phase changes. Subsequently, we applied CO2 aeration washing for the first time or low-concentrated acetic acid washing to eliminate AAEMs from MBC, reducing potential hazards in the future industrial application.Characterization results suggested that both post-processes effectively removed AAEMs from MBC, reducing the average content of Na and K to 0 mass%, Ca to 1.4 mass%, and Mg to 1.9 mass%. The Cl content was also reduced to 0.1 mass%. After removing AAEMs, the final carbon content of MBCs was as high as 90.8 mass% (dry ash free basis) with a minimum ash content of 6.4 mass% (dry basis) according to ultimate analysis. Comparison with commercial coal products showed that carbon contents were superior and ash contents were lower than those of most coal samples, suggesting that the treated MBCs are of sufficient quality for the carbon cycle industry.

Enhanced H2 gas production from steam gasification of a winery waste through CO2 capture by waste concrete fines and use of alkali catalysts

This study focused on production of a high yield of hydrogen as a clean energy source from a winery waste, through steam gasification. The experiments were conducted in a fixed bed system and a thermal analysis-mass spectrometer unit. Quarry dust waste from cement industry was used to capture carbon dioxide emissions and alkali carbonates of K, Li and Na were used as catalysts. Based on the optimum conditions derived in a previous work, the effects of sorbent/biomass ratio, catalyst loading and temperature on conversion, gas composition and quality, cold gas efficiency and yield of high purity hydrogen were investigated. The amount of carbon dioxide captured up to 700 °C was 92–97 % and at 750 °C about 83 %. At Ca/C = 1 the molar fraction of hydrogen in the product gas was 74.8 %. Sodium carbonate exhibited a better overall catalytic activity at a loading of 20 % wt. In this case, hydrogen yield and concentration were 4.7 m3/kgchar and 95.9 %, respectively and char conversion 98.1 % on a dry ash-free basis. The proposed method was proved advantageous for high purity hydrogen gas production and environmental management of wastes.

Facets of coalbed methane reservoir in East Bokaro Basin, India

The East Bokaro Basin of the Damodar valley is a potentially prospective CBM (coalbed methane) play having significant cumulative coal seam thickness, in-situ gas content, vitrinite percentage, and adequate thermal maturity. Successful CBM recovery needs a detailed understanding of the organic content, pore structures/networks, storage properties and gas flow mechanism. The present work attempts to systematically investigate East Bokaro coal for organo-petrographic controls on gas content and generation, variations in sorption capacity and saturation, pore mechanisms, cleat intensity, cleat aperture distribution and spacing. The values of in-situ gas, sorption capacity and methane concentration (C1) vary from 3.52 to 30.93 cc/g (dry ash-free basis), 15.40–32.40 cc/g (dry ash-free basis), and 66–93 vol%, respectively. The atomic ratios H/C and O/C indicate that thermally matured coal seams contain type III-IV kerogen positioned in the dry gas window. The decrease of hydrogen-containing liptinite with increasing depth reveals the function of thermal gradient on the cracking of liptinitic compounds with successive evolution of hydrocarbons and the development of a carbon-rich pore matrix. The H/C ratio is also influenced by the increasing content of vitrinite and reflectance values of deeper coal. More than 63 % of desorbed gas was determined from desorption measurement and low sorption time (τ, mainly <10 days). This demonstrates good diffusion characteristics of the studied coal. It shows the tendency of desorbed gas diffusion from pores reaches to cleat-fractures with negligible influence of secondary mineral infillings. The high-pressure sorption studies of methane on various samples indicate substantial open-pore characteristics, supporting adsorption, diffusion and gas release. The relationship of C3/C1 and C2/C1 ratios demonstrates that the hydrocarbons in coal primarily originated from the thermogenic transformation of organic matter. Such an assessment is also supported by the stable isotope (δ13C1) value that ranges between −22.70 ‰ and −57.30 ‰. However, some of the lighter isotope values (<–50 ‰) indicate a mixed origin of gases, which may be due to the influx of fresh-water to coal associated aquifers carrying bacteria received from local drainage. Geochemically and thermally altered dissolved and partially filled pores, shown by SEM photographs, negligibly influence gas sorption, diffusion, and flow mechanism in coalbeds. The pore network model signifying that the studied coal seams are microstructurally different comprises a lateral difference in pore and cleat/fracture.

Valorization of red macroalgae biomass via hydrothermal liquefaction using homogeneous catalysts

Hydrothermal liquefaction of red macroalgae species, Kappaphycus alvarezii (KA) and Eucheuma denticulatum (ED), was performed at 350 °C in the presence of 5 wt% neutral and alkali catalysts like Na2CO3, K2CO3, CaCO3, Na2SO4, NaOH, and KOH. The maximum bio-crude yield of 26.7 wt% and 18.5 wt%, on a dry ash-free basis, was obtained from Na2CO3 treatment of KA and KOH treatment of ED, respectively. The bio-crude from both feedstocks mainly consisted of cyclic oxygenates, whose selectivities were maximum in K2CO3 and CaCO3 treatments. The calorific value of the bio-crude was 38.5 MJ/kg from KA and 30.8 MJ/kg from ED, while that of biochars was 20–24 MJ/kg. A high degree of deoxygenation (64.2%) was observed in bio-crude produced from Na2SO4 treatment of KA biomass. Salts of Cl–, SO42– and K+ constituted the major inorganic portion of the aqueous phase. Maximum energy recovery (99%) was observed from the Na2CO3 treatment of ED.

Biocrude Production via Non-Catalytic Supercritical Hydrothermal Liquefaction of Fucus vesiculosus Seaweed Processing Residues

The potential of using cold water brown macroalgae Fucus vesiculosus for biocrude production via non-catalytic supercritical hydrothermal liquefaction (HTL) was studied. Demineralization, residue neutralization, and high value-added product (alginate and fucoidan) extraction processes were carried out before using the biomass for HTL biocrude production. Acid leaching was carried out using three demineralization agents: distilled water, dilute citric acid solution, and the diluted acidic aqueous by-product from a continuous HTL pilot facility. Alginate was extracted via H2SO4 and NaCO3 bathing, and fucoidan was extracted using CaCl2. Experimental data show that none of the leaching agents was greatly efficient in removing inorganics, with citric acid leaching with extensive neutralization reaching the highest ash removal efficiency of 47%. The produced 6 sets of biocrudes were characterized by elemental and thermogravimetric analyses. Short (10-min retention) HTL and the extent of leaching residue neutralization were also investigated. Highest biocrude yields were recorded when liquefying non-neutralized citric acid leaching, alginate, and fucoidan extraction residues. On the other hand, thermochemical conversions of short retention time HTL, full neutralization extent, and baseline (dried raw macroalgae) biomass performed worse. Specifically, the highest biocrude yield of 28.2 ± 2.5 wt.% on dry ash-free feedstock basis was recorded when liquefying alginate extraction residues. Moreover, the highest energy recovery of 52.8% was recorded when converting fucoidan extraction residues.

Effect of acid treatment and Na2CO3 as a catalyst on the quality and quantity of bio-products derived from the pyrolysis of granular bacteria biomass

The intense growth rate of granular bacteria biomass (GB) in anaerobic wastewater treatment units has made environmental problems with its disposal. In this research the potential of pyrolysis method to convert granular bacteria biomass to biofuels was completely investigated. The non-catalytic experiments were performed in a temperature range of 400 to 700 °C and the maximum liquid product yield on dry ash-free basis (55.0 %wt.) was obtained at optimum temperature of 550 °C. Pyrolysis of pretreated granular bacteria with 5 wt% HCl (PGB) and then impregnation with Na2CO3 (IPGB) was studied to improve the bio-oil quality as well as higher amount of synthesis gas. Feedstock pretreatment with acid decreased the gas yield in 550 °C while Na2CO3 pretreatment had reverse effect, with H2 yield (mmol/g feed) of 2.9, 2.4 and 1.8 for IPGB, GB and PGB respectively. It means Na2CO3 exhibited excellent catalytic activity toward producing hydrogen-rich hydrocarbons. Acid treatment increased bio-oil weight percent with little effect on the quality, while the IPGB pyrolysis resulted 8.3% and 8.6% decrease in the oxygenates and nitrogenates respectively and 19.5% increase in the hydrocarbons which improved the higher heating value (HHV) from 32.6 MJ/kg to 33.7 MJ/kg in comparison with GB. The raw and treated biomass was characterized by using thermogravimetric analysis (TGA-DTG), X-ray fluorescence (XRF), elemental analyses (CHNS), field emission scanning electron microscope (FESEM) and scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS). The bio-products were analyzed by a gas chromatography-thermal conductivity detector (GC-TCD), a gas chromatography-mass spectrometry (GC–MS) and CHNS.

Raman spectroscopy of biochar from the pyrolysis of three typical Chinese biomasses: A novel method for rapidly evaluating the biochar property

Biochar from the pyrolysis of rice husk, pine wood and rice straw under the temperature from 250 °C to 800 °C were obtained and characterized by Raman spectroscopy. The biochar properties and chemical structure evolution were investigated, and correlations between biochar properties and Raman spectral parameters were set up. The results indicate that pyrolysis temperature has a more significant influence on biochar yield than feedstock. The volatile content in raw biomass linearly decreases with the decrease of biochar yield, and the atom H/C ratio of biochar linearly decreases with the decrease of Vdaf (volatile content in dry ash free basis). The change characteristics of Raman bands position and bandwidth indicate that carbon order degree of biochar progressively increases with the increase of pyrolysis temperature, and detailed chemical structure of biochar from different raw biomass can significantly differ from each other. Reasonable correlations between biochar properties including yield, Vdaf, the atom H/C ratio and the fluorescence interference degree in Raman spectrum (defined as α) of biochar have been found. A series of functions were proposed for rapid evaluation of biochar properties. Specially, the correlation that H/C = 0.3652 + 2.2887∗α-2.4035∗α^2 + 0.8221∗α^3 can be universal for carbon-based fuels including biochar, coals, coal chars and bio-oil chars.

Analysis of spontaneous combustion liability indices and coal recording standards/basis

The characterization of the physical and chemical properties of coal on a standard provides an understanding of its characteristics towards spontaneous combustion. The trend of linear relationships between coal recording standards (% air-dried (ad), % dry (db) and % dry ash free (daf) basis) of 30 selected coal samples from the Witbank coalfields and spontaneous combustion liability indices were evaluated. The spontaneous combustion liability indices of these samples were evaluated by crossing point temperature (XPT), Stage II Slope, FCC (Feng, Chakravorty, Cochrane) and the Wits-Ehac tests, while the coal properties were determined from the proximate and ultimate analyses. The results obtained from these coal properties were related to different liability indices to develop trends of linear relationships using regression analysis. The ad basis indicated higher correlation coefficients than the db and daf basis for the XPT and FCC index, while the daf showed higher correlation coefficients than the ad and db basis for the Wits-Ehac index. It was found that the trend of linear relationships of these coal properties differs from one liability index to the next. The XPTs showed a better trend followed by the Stage II Slope on the coal properties among the spontaneous combustion liability indices evaluated.

Estimating the Heating Value of Coals Based on the Composition

For a wide population of coals, the heating value can be estimated based on the composition using well-known calculation formulas with an error comparable to a total error observed during experimental measurement of the heating value and heat caused by the error of determining the elemental composition. In a number of instances, the difference between the calculated and experimental values for an individual sample is much greater and is caused by the dependence of the result on the coal characteristics unaccounted for in the calculation models. The calculated and experimental heating values (dry ash free basis) strongly depend on the ash content of the coal. The difference in the binding energy of the elements in coals having varying degrees of coalification and petrographic composition plays a relatively weak role.

Statistical Clarification of the Hydrothermal Co-Liquefaction Effect and Investigation on the Influence of Process Variables on the Co-Liquefaction Effect

Hydrothermal co-liquefaction of different types of biomass has recently attracted great interest as it has the potential to reduce logistics costs and increase the biocrude yield/quality. Although a positive co-liquefaction effect (CE) has been reported in previous studies, the statistical significance of CE is uncertain, and the effects of process variables on the CE remain unexplored. In this study, the carbohydrate-rich feedstock (sawdust and spent coffee grounds) was hydrothermally co-liquefied with algal biomass (Chlorella sp. and seaweed) at 270 and 320 °C with varying mixing ratios of 25:75, 50:50, and 75:25. A statistically sound method, one-sample t-test, was, for the first time, applied to evaluate if the positive or negative CE is significantly greater or less than zero. A significantly positive CE of 22.4% (synergistic effect) on the biocrude yield was obtained in the co-liquefaction of spent coffee grounds/Chlorella sp. Co-liquefying sawdust/Chlorella sp. and spent coffee grounds/seaweed showed negative and positive values of CE, respectively, but these numbers were not statistically significant, taking the experimental error into consideration, and thus should not be considered as an antagonistic or synergetic effect for the two types of mixtures. Co-liquefaction of sawdust/seaweed exhibited a significantly negative CE (antagonistic effect) on the biocrude yield (−14.8%). The feedstock mixing ratio (varying biochemical composition of mixture) did affect the CE, which was reasoned using the knowledge of biomass model components’ interactions under liquefaction conditions. As observed, sufficient and comparable contents of protein and carbohydrate in the feedstock blends led to the synergistic effect on the biocrude yield. Temperature was also influential for the CE; for instance, increasing temperature diminished the synergistic effect in co-processing of spent coffee grounds and seaweed. Within the experimental scope, spent coffee grounds/Chlorella sp. were identified to be the most favorable feedstock combination, giving a biocrude yield of 37.2 wt %, dry ash-free basis and a synergistic effect of 22.4%, when co-liquefying at 320 °C and a mixing ratio of 50:50.

Catalytic hydropyrolysis of biomass using supported CoMo catalysts – Effect of metal loading and support acidity

Catalytic hydropyrolysis of biomass to green fuels was performed using supported, sulfided CoMo catalysts. With MgAl2O4 as support material the CoMo loading was varied between 4.1 and 12.0 wt% at constant Co/Mo atomic ratio of 0.3. Increasing the metal loading decreased the amount of oxygen in the condensed organic phase from 9.0 to 4.7 wt% on dry basis (db) and the condensable organic yield decreased from 25.2 to 22.7 wt% on dry ash free (daf) basis, corresponding to a decrease in the carbon recovery from 39 to 37%. Using zeolite H-ZSM-5 mixed with alumina as support with a CoMo loading of 4.1 wt%, the condensed organics contained only 5.2 to 6.1 wt% db oxygen. The condensable organic yield was between 23.9 and 24.4 wt% db, and the carbon recovery was 39–40%. Thus using an acidic support can remove the oxygen without decreasing the carbon recovery. The latter was ascribed to alkylation of the aromatics when the zeolite support was used.Elemental maps of the spent catalysts were obtained using STEM-EDS, showing that the CoMo phase was mainly located as monolayer MoS2 slab structures (>93%) on the support and indicated a high dispersion of cobalt, consistent with incorporation of Co into the MoS2 structure in the CoMoS phase. Potassium was observed on all the spent catalysts, indicating transfer of alkali metal from the biomass to the catalyst. Potassium may decrease the acidity of the catalyst over time, thus reducing the positive effect of using a more acidic support.

Hydrocarbon generation potential and thermal maturity of coal and coaly mudstones from the Eocene Urahoro Group in the Kushiro Coalfield, eastern Hokkaido, Japan

This study reveals the hydrocarbon generation potential and thermal maturity of coal and coaly mudstones from the Eocene Urahoro Group in the Kushiro coal basin (Kushiro Basin) of eastern Hokkaido (Japan). The coal is classified as subbituminous or high volatile C bituminous, and characterized by high hydrogen content (6.1 ± 0.4 wt%, 1σ, dry ash free basis). The hydrogen index (HI = 180–409 mg hydrocarbon/g total organic carbon) and random mean vitrinite reflectance (VRr = 0.42–0.56%) indicate that the coal and coaly mudstones in the Urahoro Group are gas- and oil-prone or oil-prone. Based on the HI and VRr values, the effective oil window starts at vitrinite reflectance ranges of 0.55 to 0.80%. The vitrinite reflectance of coal samples from the Kushiro Coal Mine is inversely proportional to the HI value, although each coal seam has the identical thermal history. This result suggests that the vitrinite reflectance of the samples in the Kushiro Coal Mine is suppressed. Based on the corrected vitrinite reflectance (non-suppressed vitrinite reflectance), the maturity of the coal in the Kushiro Basin increases towards the north. The non-suppressed vitrinite reflectance of the samples from the northernmost part of the basin (Hokuyo Area) was approximately 0.8%, which is within the start of the oil window. The maturity of the coal-bearing strata in the northern area of the basin could be affected by volcanic activity along the volcanic front. In the Hokuyo Area, the Urahoro Group overlies a sequence of Cretaceous–Eocene marine clastic rocks (Nemuro Group), which are about 3000–4000 m in total thickness, suggesting that the organic matter in the marine clastic rocks should reach higher maturity (VRr > 0.8%).

Distribution Characteristics of Coking Products and Mechanism of Tar Lightening in Preparation of High-Strength Gasification-Coke with Low-Rank Coal Blending

During the preparation of high-strength gasification-coke with low-rank coal blending, evolution of pyrolysis tar and gas is still unclear for situations where large amounts of low-rank coal are blended. Herein, the effect of low-rank coal blending on the distribution of coking products was thoroughly investigated and the mechanism of tar lightening was studied by simulating the coking process with 1 kg laboratory-scale coke oven. The results showed that more liquids but less gases were formed compared to the theoretically calculated values due to a stronger cohesive interaction in the coal blending system. Moreover, the gas yield and volatile matters in dry ash-free basis (Vdaf) showed an opposite linear correlation for single coal and blended coal, probably due to this strong cohesive interaction. The facileness of long-chain aliphatic hydrocarbons to crack into low-molecular-weight hydrocarbons is attributed to their weaker interactions with more low-rank coal blends. The low-rank coal blending significantly promoted the release of phenols due to the presence of hydrogen-donor groups. In addition, more fractured branched alkanes inhibited the deep condensation of free radicals (cohesive compounds), which led to tar lightening in the low-rank coal blending system. In contrast, in the caking coal blending system (without the addition of low-rank coal), aromatization of fractured olefin terminals promoted deep condensation of cohesive free radicals, resulting in the formation of more heavy tar. The current study also demonstrated that the conversion of heavy tar into light products could be promoted by adjusting the input of low-rank coal during the caking coal upgrading process, thereby increasing the profitability of the coking process.

Hydrothermal carbonization of biogas digestate: Effect of digestate origin and process conditions

Hydrothermal carbonization (HTC) solids were produced in a 250-ml batch reactor from three different digestates at varying temperatures (170, 190, 210, 230, and 250 °C) and 2 and 5 h reaction time. Three potential feedstocks of biogas plants were tested: organic household waste, cow manure, and energy crops. The proximate composition, elemental composition, heating values, and thermal stability of the HTC solids were characterized. The dry ash-free basis yields and carbon recovery of HTC solids decreased with increasing HTC temperature and time. The HTC solids from energy crop digestate had the highest yields (dry ash-free basis) except at the temperature of 250 °C. Increased HTC severity was found to have a positive effect on the dry basis carbon content and leads to a higher heating values (HHV) of cow manure digestate HTC solids. The preferred reaction condition for organic household waste digestate and energy crop digestate HTC solids was found to be 210 °C for 5 h, because of the highest HHV (dry basis) and the overall combustion performance was reached. Enhancing HTC temperature increased the peak intensity of functional groups of cow manure digestate HTC solids. Scanning electron microscopy imaging showed the fibrous structure of the plants from the digestates was mostly deconstructed at 250 °C-5 h. Experimental results indicated that both digestate origin and HTC condition influenced the properties of the HTC solids.

New insights into the effect of pressure on catalytic hydropyrolysis of biomass

Catalytic hydropyrolysis of beech wood has been conducted in a fluid bed reactor at 450 °C with a sulfided CoMo catalyst followed by a fixed bed hydrodeoxygenation (HDO) reactor with a sulfided NiMo catalyst at hydrogen pressures between 3.0 and 35.8 bar. Using both reactors the condensable organic yield (condensed organic and C4+ in gas) varied between 18.7 and 21.5 wt% dry ash free basis (daf) and was independent of the hydrogen pressure. At 15.9 bar hydrogen or higher the condensed organic phase was essentially oxygen free (<0.01 wt% dry basis (db)), but decreasing the hydrogen pressure to 3.0 bar increased the oxygen content to 7.8 wt% db. The char and coke yield was close to constant (11.0–12.7 wt% daf) at hydrogen pressures between 15.9 and 35.8 bar, but increased to 15.7 wt% at 3.0 bar hydrogen due to an increase in the polymerization of pyrolysis vapors. The measured carbon content on the spent catalysts from both the fluid bed and HDO reactor showed that coking of the catalysts increased when the hydrogen pressure was decreased below 15.9 bar. The increased coking at low hydrogen pressure (<15.9 bar) was ascribed to the polymerization of the more reactive oxygenates produced in the fluid bed reactor.

Pyrolysis of sewage sludge by solid heat carrier

The experimental study of fast pyrolysis of dried sewage sludge in the retorting system with solid heat carrier was performed. The yield of the main pyrolysis products such as gas, oil, pyrogenic water, and solid residue (pyrolytic char) was measured in the 490–580 °C range. The maximum oil yield in an amount of 38.5 wt% on dry ash free basis was registered at a temperature of 550 °C. The gas chromatographic-mass spectrometric (GC-MS) analysis of pyrolytic oil allows the identification of 58 hydrocarbons of different structures and different classes such as aliphatic, aromatic, oxygenated and nitrogen-containing compounds. The group composition of the obtained oil makes it possible to identify it as an analog of crude oil, which can be processed by standard technologies. The technological scheme of the facility for pyrolysis of sewage sludge based on the technology Galoter for the thermochemical processing of low-grade fuels was proposed with corresponding material and heat balance.

Thermochemical behavior and characterization of palm kernel shell via TGA/DTG technique

Abstract This study investigates characterization and thermal decomposition of palm kernel shell (PKS) biomass. PKS is heated from 25 °C to 1000°C using TG/DTG analysis using air atmosphere with a flow rate of 100 ml.min-1 at four different heating rates 10, 20,30, 40°Cmin-1. The physiochemical properties such as proximate analysis, ultimate analysis, heating values, X-Ray Fluorescence (XRF), Field Emission Scanning Electron Microscopy (FESEM), and Brunauer-Emmett-Teller (BET) were determined. The results of the ultimate analysis show a higher amount of carbon and hydrogen contents which results in a higher heating value of palm kernel shell (PKS). The higher heating value determined by bomb calorimetric method was 17 MJ/kg on dry ash free basis. The FESEM analysis shows that PKS has a porous structure which facilitates the volatile matter release necessary for bio-energy production. It can be concluded from this study that; palm kernel shell has good potential to be converted into biofuels or used as fuel for energy.