Search

Direct ink writing was used for 3D printing of tubular Al2O3 membrane support. Agar-based ink mixtures were prepared as a paste with a proper viscoelastic behavior in achieving printing. Using agar only for mixing with Al2O3 slurry in preparing the ink mixtures showed the flow behavior resulting in failure to print the Al2O3 tube due to too low viscosity of the ink mixture—100 Pa at 40°C. However, the introduction of Hydroxyethyl cellulose (HEC) as thickener and Polyethylene glycol 1500 (PEG 1500) as lubricant helped improve the behavior of the ink mixtures to be more proper paste for printing. The amounts of HEC were varied from 0 to 2wt% of solid loading. At 2wt% HEC, the ink mixture was able to be printed highest, compared to the other ink mixtures. However, the 2wt% HEC-using ink mixtures possessed the highest sintering shrinkage at 12%, while its relative density was highest at 70%. The results indicated that it was possible to print the alumina membrane tube if its fidelity was improved further.

Organosolv lignin extracted from sugarcane bagasse (BG-lignin) and commercial grade lignin (Comm-OS) were use as starting materials in this study. From our previous work, aromatic furan (2,3-dihydrobenzofurn) was mainly produced from fast pyrolysis of BG-lignin and Comm-OS at 400–600 °C while alkyl phenol and phenol are more favorable at 700 °C. However, more thermal fragmentation was simultaneously redundant which results in low aromatic selectivity. In this work, aromatic production from lignin with molecular sieve ZSM-5 catalysts was studied using Py-GCMS instrument with biomass to catalyst ratio (B:C) of 1:1, 1:5, and 1:10. Aromatic furan and monolignol (H-unit, G-unit, and S-unit) were transform to hydrocarbon species with addition of ZSM-5 catalyst according to elimination of side chain by demethoxylation, dehydroxylation, and dealkylation reactions. Maximum aromatic production was found at B:C of 1:10 for both Comm-OS and BG-lignin of 87.31% and 88.22%, respectively, while aliphatic hydrocarbon was more abundant for BG-lignin of 43.21% (1:5). Moreover, ZSM-5 exhibit instinctive performance on MAHs and PAHs production especially at B:C of 1:5 and 1:10. Nevertheless, polymerization between MAHs results in PAHs also observed for both Comm-OS and BG-lignin. From the result, transformation of aromatic furan could be limited by introduction of molecular sieve ZSM-5 which enhance the oxygen elimination from phenol derivative and favorable for aromatic and BTX production.

Fly ash (FA), a by-product of coal combustion, is considered as waste due to its high content of lime and other impurities and is either disposed of in landfills or recycled. Utilization of waste FA as a starting material for the synthesis of zeolite catalysts is a promising solution to reuse this waste. Meanwhile, de-oiled Millettia (Pongamia) pinnata seed waste (PPW) is produced in large amounts from the bio-oil extraction process. This waste is of no value due to its toxicity. However, it was previously shown that the fast pyrolysis of PPW to produce biofuels resulted in oleic acid and other oxygenated (O)-compounds as the main composition (67.2%) with smaller levels of hydrocarbons (HCs). In this work, the catalytic upgrading fast pyrolysis of PPW over the FA-derived ZSM-5 (FA-ZSM-5) and zeolite X (FA-X) catalysts to enhance the formation of HCs was performed using a pyrolyzer interfaced with gas chromatography-mass spectrometry (Py-GCMS), using various biomass to catalyst (B:C) weight ratios (1:1, 1:5 and 1:10). The FA-ZSM-5 and FA-X were derived from FA by alkali hydrothermal and alkali fusion methods, respectively. The result demonstrated that the pyrolysis vapors of PPW had a high content of undesirable components, such as carboxylic acids, oleic acid and other O-compounds (67.2%), whereas the aliphatic and aromatic HC contents were markedly lower. The presence of the synthesized FA-ZSM-5 or FA-X catalysts resulted in a major improvement in the pyrolysis vapor quality. Selectivity on total HCs (aliphatic and aromatic) was significantly increased with greater catalyst contents for both FA-ZSM-5 (90.6%) and FA-X (84.9%). FA-ZSM-5 exhibited a high selectivity for aromatic HCs (82.6%) while zeolite-X showed a higher selectivity towards aliphatic HCs (71.0%). The level of O-compounds was substantially decreased to 1.12% and 21.9% with FA-ZSM-5 at a B:C ratio of 1:10 and FA-X at a B:C ratio of 1:5, respectively. In addition, FA-ZSM-5 and FA-X reduced the content of nitrogenated-compounds from 24.8% (no catalyst) to 8.3% and 0.0%, respectively. Overall, the results suggest that FA-ZSM-5 had a higher HC selectivity and was more effective in promoting deoxygenation reactions, whereas FA-X significantly enhanced the denitrogenation reaction.

Fast pyrolysis of Millettia (Pongamia) pinnata waste (PPW) was performed using a scaled-up 180-cm drop-tube pyrolyzer with fly ash (FA)-derived ZSM-5 (FA-ZSM-5) as a deoxygenation and denitrogenation catalyst to upgrade the liquid products. The oil from P. pinnata is typically extracted to produce bio-fuel leaving a large amount of PPW that has some 20% (v/v) oil content. Since the PPW is inedible, due to its toxicity from karanjin and di-ketone pongamol, it represents a potential non-food competing ‘green’ biofuel feedstock. The FA-ZSM-5 catalyst applied in this work was synthesized using alkali hydrothermal treatment of coal FA to yield FA-ZSM-5 with a 329 m2/g surface area and 37.18 A pore diameter. Pyrolyzer-gas chromatography-mass spectrometry was used to locate the optimal operating window prior to executing a scaled-up reactor operation at 400–700 °C). A maximum bio-oil yield of 43.1% by proportion was obtained at 500 °C, while the solid and gas products were 32.5% and 24.4%, respectively. Oleic acid was a major component in the bio-oil obtained from the non-catalytic condition, while ketones were prominent (79.4%) when FA-ZSM-5 was used, albeit with a low hydrocarbon (HC) selectivity. From the carbon chain length analysis, thermal cracking to smaller molecules was dominant in the presence of the FA-ZSM-5 catalyst, inducing a low HC yield in the liquid product.

Reducing anthropogenic CO2 emissions and lowering the concentration of greenhouse gases in the atmosphere have quickly become one of the most urgent environmental issues of our age. Carbon capture and storage (CCS) is the option for reducing these harmful CO2 emissions. While a variety of technologies and methods have been developed, the separation of CO2 from gas streams is still a critical issue. Apart from establishing new techniques, the exploration of capture materials with high separation performance and low capital cost are of paramount importance. Nanoporous carbon derived from leaf of cattail flower that found in all areas throughout Thailand, the biomass was previously pyrolyzed at 500 to 700°C and the produced chars were further activated with NaOH, KOH, Na2CO3 and K2CO3 subsequently. Afterwards, the resulting materials were characterized by Scanning electron microscopy, Fourier-transform infrared spectroscopy and Raman scattering measurement. From this investigation, produced activated carbon will be efficient as an option for CO2 emission control.

De-oiled Millettia (Pongamia) pinnata seed waste (PPW) is produced in large amounts after the oil extraction process, but still contains 20% (w/w) oil residues. These raw wastes are of no value and consist of toxic compounds, such as karanjin and di-ketone pongamol, with an overall composition of 45–51% carbon and 5–7% hydrogen and 91% combustible compounds, including fixed carbon and volatile matter. The conversion of PPW to biofuel via pyrolysis is one potential use. Fast pyrolysis of PPW was performed at 400, 500 and 600 °C in a micro-batch pyrolyzer interfaced with gas chromatography-mass spectrometry (Py-GC/MS). However, the pyrolytic products contained a high level of oxygenated- (34.1–66.5%) and nitrogenated-compounds, giving poor fuel properties, such as a high acidity and viscosity. Oxygenated compounds were mainly carboxylic acids, ketones, alcohols and esters. The introduction of the zeolite (USY) catalyst into the pyrolysis of PPW improve the pyrolytic liquid properties. The oxygenated compounds underwent undergoing decarbonylation, decarboxylation and dehydration reactions and further conversion to aliphatic and aromatic hydrocarbons. Pyrolysis at 500 °C of small sized PPW particles (125–425 μm) at a PPW: USY ratio of 1:5 gave the highest hydrocarbon yield (99.0%). The selectivity for monocyclic aromatic hydrocarbons at 500 °C was increased from 4.7–17.4% to 52.5–56.5% when the biomass: catalyst ratio was increased from 1:1 to 1:5. Moreover, the USY catalyst promoted carbon chain scission producing shorter hydrocarbons (C5–12), which was enhanced by the decarboxylation and dealkylation of the alkylated oxygenated compounds.

Perovskite-type mixed oxides La1−xCexCoO3 (x = 0, 0.2, 0.4) were synthesized by sol–gel method via polyvinyl alcohol (PVA) as gelating agent. LaCoO3 and CeO2 phases were presented while intermediate phase, La(OH)3, disappeared during LaCoO3 transformation. Introduction of Ce decreased crystal size of catalyst from 22.18 to 13.38 nm. Particle size and specific surface area were in the range of 9.58–13.72 μm and 6.03–9.23 m2/g, respectively. The addition of Ce increased the reduction temperature which indicated the strong interaction between Co and perovskite structure. Catalytic activity was investigated by steam reforming of toluene at 500–800 °C. Conversions of carbon and hydrogen to CO, H2, and CH4 at steam per carbon ratio (S/C) of 2:1 were clearly higher than 4:1. Increasing S/C ratio to 4:1 inhibited syngas production efficiency by combustion and water–gas shift reaction. The presence of Ce in the catalyst did not improve activity of catalyst significantly. However the metal enhanced stability by promoting the formation of filamentous carbon on the surface such that the active sites are still accessible to the active gas during the experiment. After reforming, catalysts were transformed to La(OH)3, Co0, and Ce4O7 phases and no significant deterioration in catalytic performance was detected after 6 h. In this study steam reforming of toluene over La0.6Ce0.4CoO3 at 800 °C with S/C 2:1 yielded highest carbon conversion as CO and hydrogen conversion as H2 of 64.42 and 63.23 %. The LHV and H2/CO of produced gas at this optimum condition are 4.22 MJ/N m2 and 2.91, respectively.

Hybrid metal ion and polyvinyl alcohol (PVA) was prepared to obtain La 1− x Ce x NiO 3 ( x = 0, 0.2, and 0.4) perovskite-type catalyst powder by sol-gel method. Metal ion to PVA monomer molar ratio was assigned at 1:1. The metal ion formed into complex precursors with alkoxide to improve the elemental dispersion and prevent agglomeration of obtained catalyst which is strongly related to activity and stability on syngas generation. As-prepared catalysts were calcined at 800 °C and characterized. X-ray diffraction pattern confirmed high crystalline of LaNiO 3 perovskite structure and additional CeO 2 phase was founded when La was partial substituted by Ce. The crystal size and particle size of La 1− x Ce x NiO 3 tended to decrease with higher Ce content. SEM and EDS results confirmed good elemental dispersion with homogeneous structure and low agglomeration. Particle size and surface area were in the range of 13.85–16.70 μm and 2.40–5.87 m 2 /g, respectively. Temperature programmed reduction (TPR) of prepared catalyst show highest H 2 consumption at 390 °C and 700 °C which were attributed to the partial reduction of Ni 3+ to Ni 2+ and Ni 2+ to Ni 0 , respectively. Activity of catalyst on steam reforming of tar was investigated using toluene as model compound in a fixed bed quartz reactor at 500–800 °C with steam/carbon molar ratio of 2:1. Carbon and hydrogen conversion were interpreted in term of CO 2 , CO, H 2 , and C x H y as CH 4 . The effect of operating temperature appeared to improve favorable fuel gas species formation in terms of selectivity and quantity. Addition of La 0.6 Ce 0.4 NiO 3 catalyst promoted conversion of toluene to CO and H 2 at the highest yield of 57.26% and 76.62% at 800 °C, respectively. Moreover, catalysts showed favorable stability because no deactivation was observed during the 180 min of test. LHV of syngas obtained can be used for power production without need for auxiliary fuel.

La1-xCexCoO3 (x=0, 0.2, and 0.4) perovskite-type mixed oxides using polyvinyl alcohol (PVA) as complexing agent at two molar ratio of metal ion to PVA (1:1 and 1:2) were successfully prepared by sol-gel process. The precursor included lanthanum (II) nitrate hexahydrate, cerium (II) nitrate hexahydrate, and cobalt (II) nitrate hexahydrate where polyvinyl alcohol was added as complexing agent. The suitable condition of Cerium (Ce) substitution and PVA molar ratio were established for further application in hydrocarbon conversion to high value added products. TGA thermogram of as-prepared precursor showed that PVA absolutely decomposed at temperature higher than 500°C. XRD patterns of calcined catalyst showed both LaCoO3 rhombohedral and CeO2 cubic structures that confirmed the formation of mixed crystal structure. Nevertheless, Co3O4 slightly appeared with low peak intensity which came from the oxidation reaction of as-prepared catalyst during calcinations. XRD showed that PVA did not effect to crystal structure of synthesized catalyst. Higher PVA content added in the precursor cause the reduction of crystal growth of catalyst in calcinations step. In contrast, morphology of catalyst is directly related with PVA content such that the spongy and sheet-like structure were formed with increasing PVA content which prevented the agglomeration of particles. The results showed that PVA content play an important role in morphology of perovskite-type mixed oxide catalysts but did not affected to their crystal structures.

Perovskite-type oxides catalyst are of interest for various application such as auto-thermal reforming (ART), catalytic wet air oxidation (CWOA) and piezoelectric (PZT). In this paper, La1-xCexNiO3 (x= 0-0.4) perovskite-type oxides have been prepared b sol-gel process using PVA. The precursor was mixed metal ion and PVA with a mole ratio of 1:1 and 1:2. The decomposition during the calcinations process was evaluated by thermogravimetric analysis and differential thermal analysis. Phase of synthesized materials were characterized with X-ray diffraction. Morphological analysis and elemental composition of catalysts was determined by Scanning electron microscope and energy dispersion spectroscopy. The characterization results show that highly crystalline and homogeneous phase of these perovskite oxides were successfully synthesized by the sol-gel method via PVA as a complexing agent.