Process modeling for parametric study on oil palm empty fruit bunch steam gasification for hydrogen production

Biomass steam gasification with in-situ carbon dioxide capture using CaO exhibits good prospects for the production of hydrogen rich gas. The present work focuses on the process modeling for hydrogen production from oil palm empty fruit bunch (EFB) using MATLAB for parametric study. The model incorporates the reaction kinetics calculations of the steam gasification of EFB (C_3.4H_4.1O_3.3) with in-situ CO₂ capture, as well as mass and energy balances calculations. The developed model is used to investigate the effect of temperature and steam/biomass ratio on the hydrogen purity, yield and efficiency. Based on the results, hydrogen purity of more than 76.1 vol.% can be achieved. The maximum hydrogen yield predicted at the outlet of the gasifier is 102.6 g/kg of EFB. It is found that increment in temperature and steam/biomass ratio promotes hydrogen production. However, it is also predicted that the efficiency decreases when using more steam. Due to the still on-going empirical work, the results are compared with published literatures on different systems. The comparison shows that the results are in agreement to some extent due to the different basis.     

Mechanical properties of polypropylene composite reinforced with oil palm empty fruit bunch pulp

In this study, oil palm empty fruit bunch (EFB) pulp was used as reinforcing agent in polypropylene composite. EFB pulp was prepared using soda pulping with different concentrations of sodium hydroxide (NaOH) solution. Overall, the tensile and flexural properties specifically the strength and the toughness showed improvement as the NaOH content in the treatment was increased. This was attributed to lower probability for EFB pulp to agglomerate and the production of higher aspect ratio pulp fibers. Scanning electron microscopy analysis showed evidence of the reduction in EFB bundles diameter after NaOH treatment. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Mechanical properties and fire retardant behavior of polyurethane foam reinforced with oil palm empty fruit bunch

The objective of this study was to investigate the effects of isocyanate/hydroxyl ratio and ammonium polyphosphate (APP) content on the properties of polyurethane foam. Polyurethane (PU) foam was prepared from polymeric diphenylmethane diisocyanate and polyethylene glycol with molecular weight of 200, reinforced with oil palm empty fruit bunch (EFB) using one shot process. The effect of EFB content on the properties of PU foam was also studied. It was noticed that EFB enhanced the properties of the PU foam. This was due to EFB acting as hard segment in PU foam system. The NCO/OH ratio played an important role in determining the properties of the PU foam produced. However, since EFB is a highly flammable material, APP was introduced to the PU foam system. From the results, APP improved the fire retardant behavior of the PU foam. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Thermal and mechanical properties of injection moulded heat-treated oil palm empty fruit bunch fibre-reinforced high-density polyethylene composites

ABSTRACT

Oil palm empty fruit bunch (OPEFB) was heat treated at 180°C using a vacuum oven for one hour, extruded and compounded with high-density polyethylene at 10%, 20% and 30% weight fraction. The composites then were injection moulded into dumb-bell shaped specimens. The effect of composition and heat treatment on the thermal properties of composites were investigated using Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The tensile and flexural properties were also tested using an Instron Universal Testing Machine. TGA shows an increase in the degradation peak temperature of the heat-treated composites. DSC revealed an increasing trend in the degree of crystallinity (X_c) of the matrix as the heat-treated empty fruit bunch was used as a filler. An increment in the tensile modulus and tensile strain were observed for the treated fibre composites. In addition, the tensile strength value was increased for treated fibre composites with lower fibre loading.     

Effect of silane-based coupling agents and acrylic acid based compatibilizers on mechanical properties of oil palm empty fruit bunch filled high-density polyethylene composites

The mechanical properties of composites consisting of high-density polyethylene (HDPE) and oil palm fibrous wastes—that is, empty fruit bunch (EFB)—have been investigated. Tensile modulus showed an increase, whereas tensile strength, elongation at break, and impact strength decreased with increasing filler loading. The strong tendency of EFB to exist in the form of fiber bundles and the poor filler–matrix interaction is believed to be responsible for the poor strength displayed by the composites. Attempts to improve these properties using two types of coupling agents, that is, 3-aminopropyltrimethoxysilane (3-APM) and 3-aminopropyltriethoxysilane (3-APE) and two types of compatibilizers, poly(propylene–acrylic acid) (PPAA) and poly(propylene–ethylene–acrylic acid), (PPEAA), are described. While almost all chemical treatments increased the stiffness of the composites, limited improvement has been observed in the case of tensile strength. This have been attributed to the presence of fiber bundles that remain intact even after several types of chemical treatment have been carried out. Thus, the role of EFB as reinforcing agent is not fully realized. Scanning electron microscopy (SEM) micrographs revealed that the main energy-absorbing mechanisms contributing towards toughness enhancement is through the fiber bundle pull-out process. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 2189–2203, 1998     

The effect of hexamethylene diisocyanate modified ALCELL lignin as a coupling agent on the flexural properties of oil palm empty fruit bunch – polypropylene composites

ALCELL lignin has been employed as a coupling agent in oil palm empty fruit bunch (EFB)–polypropylene (PP) composites. The lignin has been chemically modified with hexamethylene diisocyanate (HMDI). Evidence for the reaction between HMDI and lignin has been observed by using Fourier transform infrared (FTIR) analysis. The effect of lignin as a coupling agent on the flexural properties has been studied. The results show that the HMDI‐modified lignin is able to impart greater compatibility between EFB and PP. This is reflected in the greater flexural strength shown by the composites with HMDI‐modified lignin than those with the unmodified lignin. Scanning electron microscopy studies show that HMDI‐modification of lignin results in a better blending and compatibility between lignin and PP matrix. The glass transition temperature of lignin increases as the level of HMDI modification is increased. © 2001 Society of Chemical Industry     

Hydrogen production by biomass gasification in supercritical water: A systematic experimental and analytical study

Hydrogen production from biomass gasification in supercritical water is a new technology, which was developed in last two decades. Biomass energy of low quality can be converted to hydrogen energy of high quality by supercritical water gasification. Particularly, supercritical water gasification is an elegant way of wet biomass utilization. Up to now, many important progresses have been made in supercritical water gasification technology by the studies of researchers around the world. Since 1997, supercritical water gasification, which include reaction system, rule of biomass gasification and theory, have been studied in State Key Laboratory of Multiphase Flow in Power Engineering of Xi’an Jiaotong University. In this paper, we summarize the results from systematic experimental and analytical study on biomass gasification in supercritical water in our laboratory. Also, the development status and future prospect on supercritical water gasification is evaluated.     

The effect of coupling agents on the mechanical and physical properties of oil palm empty fruit bunch–polypropylene composites

Oil palm empty fruit bunch–polypropylene (EFB‐PP) composites have been produced using a twin‐screw extruder as the compounding equipment. Two levels of EFB were employed, 40 % and 60 % of the total weight of the sample. Three types of coupling agent, maleic anhydride‐modified polypropylene (commercial name Epolene E‐43), polymethylene(polyphenyl isocyanate) (PMPPIC) and 3‐(trimethoxysilyl)‐propylmethacrylate (TPM), were used. Overall, all coupling agents imparted considerable improvements in the flexural properties, E‐43 showing the highest enhancement. However, only E‐43 was observed to improve impact strength and tensile properties of the composites. All composites with coupling agents showed lower water absorption and thickness swelling. The absorption and swelling decreased as the loading of the coupling agents was increased. © 2000 Society of Chemical Industry     

High-yield hydrogen production by supercritical water gasification of various feedstocks: Alcohols,glucose, glycerol and long-chain alkanes

Continuous supercritical water gasification (SCWG) of various feedstocks of C1–C16 was conducted to produce hydrogen-rich gas. These feedstocks represent model compounds of biomass such as methanol/ethanol (alcohol-type), glucose and glycerol (byproducts of biodiesel synthesis), and model compounds of petroleum fuels such as iso-octane/n-octane (gasoline), n-decane/n-dodecane (jet fuels) and n-hexadecane (diesel). Almost complete gasification of all the feedstocks was achieved at 25 MPa, 740 °C and 10 wt% with low total organic carbon values of their liquid effluents. The hydrogen gas yields of each feedstock were very similar to the theoretical equilibrium yields estimated by Gibbs free energy minimization. SCWG at different gasification temperatures (650 and 740 °C) and concentrations (10 and 20 wt%) revealed that methanol and ethanol (alcohols), the simple oxygenated hydrocarbons, were easier to be gasified, producing negligible amounts of liquid products, when compared with long-chain hydrocarbons (iso-octane and n-decane) under the identical conditions. When the feedstock concentration was increased from 10 to 20 wt%, the equilibrium hydrogen ratio from iso-octane gasification decreased from 1.02 to 0.79 while that of n-decane increased from 1.12 to 1.50, implying that a branched hydrocarbon may be more resistant to gasification in supercritical water.     

Catalytic hydrogen production from 2-propanol in supercritical water: Comparison of some metal catalysts

The gasification of organics in supercritical water is a promising method for the direct production of hydrogen at high pressures, and in order to improve the hydrogen yield or selectivity, activities of various catalysts are evaluated. In this study, hydrogen production from 2-propanol over Ni/Al₂O₃ and Fe–Cr catalysts was investigated in supercritical water. The experiments were carried out in the temperature range of 400–600 °C and in the reaction time range of 10–30 s, under a pressure of 25 MPa. The hydrogen yields and selectivities of Ni/Al₂O₃ and Fe–Cr used in this study, and those of Pt/Al₂O₃ and Ru/Al₂O₃ used in our previous work were compared. The hydrogen contents of the gaseous products obtained by using Ni/Al₂O₃ and Fe–Cr were measured as 62 mol% and 70 mol%, respectively, at low temperatures and reaction times. However, the hydrogen yields remained in low levels when compared with that of Pt/Al₂O₃ used in previous study. Pt/Al₂O₃ was established to be the most effective and selective catalyst for hydrogen production. During the catalytic gasification of a 0.5 M solution of 2-propanol, hydrogen content up to 96 mol% and hydrogen yield of 1.05 mol/mol 2-propanol were obtained.     

Modification of oil palm empty fruit bunches with maleic anhydride: The effect on the tensile and dimensional stability properties of empty fruit bunch/polypropylene composites

Oil palm empty fruit bunch (EFB)‐filled polypropylene (PP) composites were produced. The EFB filler was chemically modified with maleic anhydride (MAH). The effects of the filler size and chemical modification of EFBs on the tensile and dimensional stability properties of EFB–PP composites were studied. The composites with MAH‐treated EFBs showed higher tensile strengths than those with untreated EFBs. This was attributed to the enhanced compatibility between the MAH‐treated EFBs and PP matrix, as shown in a scanning electron microscopy study. Fourier transform infrared analysis showed evidence of C?C and C?O bonds from MAH at 1630 and 1730 cm^?1, respectively. The MAH‐treated PP composites showed lower water absorption and thickness swelling than those with untreated EFBs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 827–835, 2003     

Polyurethane composites based on oil palm empty fruit bunches: Effect of isocyanate/hydroxyl ratio and chemical modification of empty fruit bunches with toluene diisocyanate and hexamethylene diisocyanate on mechanical properties

This study focuses on the effect of isocyanate (NCO)/hydroxyl (OH) group ratios and chemical modification of oil palm empty fruit bunches (EFBs) with toluene diisocyanate (TDI) and hexamethylene diisocyanate (HMDI) on the mechanical properties of EFB–polyurethane (PU) composites. The tensile, flexural, and impact properties are affected by the NCO/OH ratios. The tensile strengths, flexural strengths, and toughness increase as the NCO/OH increases; however, the modulus decreases. The reduction in the modulus is attributable to the increased flexibility of the PU linkages. Chemical modification of the EFBs increases the tensile strength, flexural strength, and toughness; however, the modulus is lowered as the percentage of treated EFB is increased. Impact strength results show that the strength increases as the NCO/OH ratio is increased. At NCO/OH ratios of 1.0 and 1.1, the composites with HMDI‐treated fibers exhibit higher impact strength than those with TDI‐treated and untreated fibers, respectively. This may be due to the longer and more flexible chain length of HMDI as compared to TDI, which enables the composites to absorb more energy before failure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Ruthenium(IV) dioxide-catalyzed reductive gasification of intractable biomass including cellulose, heterocyclic compounds, and sludge in supercritical water

Catalytic reduction gasification in the presence of ruthenium(IV) dioxide (RuO₂) in supercritical water was used to decompose intractable biomass. The gasification of model biomass samples (glucose, cellulose, and heterocyclic compounds), and low-purity biomass samples obtained from a paper-recycling facility (paper sludge) and from a sewage treatment plant (sewage sludge) were studied. In clear contrast to another catalysts, the RuO₂ catalyst completely gasified cellulose to produce mainly hydrogen, methane, and carbon dioxide under various conditions (e.g., 673 K at 30 MPa and 773 K at 50 MPa). As for heterocyclic compounds, nitrogen compounds did not deactivate the RuO₂ catalyst; the gasification of carbazole proceeded completely. Furthermore, paper sludge was almost completely decomposed in supercritical water with RuO₂ at 723 K.     

Transition metal and metal oxide catalysed gasification of carbon by oxygen,water, and carbon dioxide

The oxygen transfer mechanism is examined for transition metal and metal oxide catalysed carbon gasification by oxygen, water, and carbon dioxide. The mechanism appears valid for the C-O₂ reaction due to the availability of weakly bound oxygen in the bulk metal oxide or on the surface of a metal oxide or a metal in an oxygen atmosphere. In water and carbon dioxide atmospheres, only oxygen strongly bound to the metal or metal oxide is present, resulting in negligible activity for carbon gasification through this mechanism. When the catalyst is present as a reduced metal, a different mechanism for catalysed gasification involving direct breakage of carbon-carbon bonds by the metal is suggested.     

Performance evaluation of modified fabricated cotton membrane for oil/water separation and heavy metal ions removal

Preparation of effective membrane with special surface treatment for oil/water separation having promising future and low manufacturing cost. The suggested membrane was fabricated by a simple treatment via increasing the hydrophilicity of the cotton fabric surface. The cotton fabric was impregnated in poly(acrylic acid-co-N-methylol acrylamide), poly(AA-co-NMA), where NMA acts as bonding agent. Sodium hypophosphite (SHP) was added to the modification solution to enhance the bonding between the cotton fabric and the PAA. The modified fabric was thermally dried and cured at different temperatures. It was found that, the presence of 3.5% NMA and addition of 5% SHP to the modification solution then curing at 190°C gave the highest amount of bonded PAA to the cotton fabric. The success of the modification process was confirmed by scanning electron microscope, Fourier transformer infrared and the increase in the contact angle of the cotton fabric after modification. Furthermore, the prepared membrane was evaluated for oil (n-hexane, toluene, and petroleum ether)/water separation and also for heavy metal ions removal (Cd²⁺ and Co²⁺). Neutralization of the produced membrane with ammonium hydroxide resulting in a higher contact angle and consequently higher separation efficiency for oil/water mixtures and higher performance for heavy metal ions removal compared to the unneutralized one.     

Au and Cu recovery from printed boards by decomposition of epoxy resin in supercritical water

The recovery of Au and Cu from a printed board using supercritical water was studied, and the effects of the treatment with and without an oxidant on the components of the printed board were compared.Over 99 wt.% of metallic Au and metallic Cu was recovered in the solid form by oxidant-free supercritical water treatment at 400 °C and 25 MPa. However, the maximal removal of solid organics was 70 wt.% due to char-generation. Promotion of hydrolysis and inhibition of char-generation enhanced the removal of solid organics to nearly 90 wt.% at 380 °C.Under oxidative conditions, complete separation of solid organics from the inorganics occurred within 60 min. Metallic Au was unaltered and successfully recovered. Over 90 wt.% of metallic Cu was oxidized within 5 min, and only Cu oxides were recovered after 30 min. Oxidation of organics was promoted by coexisting Cu compounds contained in the printed board.     

Catalytic supercritical water oxidation of tri-n-butyl phosphate: Process optimization by response surface methodology and cytotoxicity assessment

Catalytic supercritical water oxidation (SCWO) of an organophosphate flame retardant, namely tri-n-butyl phosphate (TNBP) was studied. Firstly, copper oxide nanoparticles (NPs) were synthesized in SCW and their properties were characterized by various analyses. Afterwards, their catalytic performance was investigated under different conditions including reaction temperature (400–500 °C), TNBP volume percentage in the feed (1–4%), oxidant ratio (0–2) and reaction time (50–150 min) based on response surface methodology (RSM). The synthesized CuO NPs had an average particle size of 30 nm with a narrow distribution. According to RSM analysis, the reaction temperature and time are the most significant factors; whereas, the impact of the other factors, especially TNBP volume percentage in the feed, was found to be negligible. Overall, excellent performance was achieved under optimal conditions found by the RSM, which was reaction temperature of 500 °C, TNBP volume percentage of 4%, oxidant ratio of 1.5, and reaction time of 90 min. The TOC removal efficiency as an indicator of TNBP degradation was about 99%. Finally, in vitro cell viability assays for the cytotoxicity evaluation of fresh and SCW-treated solution were applied. The results of MTT showed that SCWO converts TNBP into by-product that did not induce any cytotoxicity.     

Reductive atmosphere of supercritical water with RuO2 resulting in TcO2 colloid: Spectroscopic, morphological and crystallographic study on solutions and precipitates in Hastelloy C-22

In order to study the complicated behavior of technetium observed under various conditions of supercritical water (SCW), i.e. quantitative transfer to solid phase, strong adsorption onto the metal surface, or efficient dissolution from the metal surface, solutions and precipitates prepared in reactors made of Hastelloy C-22 in contact with the SCW containing technetium solutions were studied by absorption spectroscopy, TEM, EDX and electron diffraction. Under SCW with or without H₂O₂, NiCr₂O₄ and NiMoO₄ was produced as the scales (corrosion products) of Hastelloy C-22. Under SCW with RuO₂ the formation of colloidal structure comprised of ruthenium metal and TcO₂, which may be named as “Tc-Ru-Colloid”, were observed. It is worthy of note that the formation of TcO₄²⁻ from pertechnatate TcO₄⁻ (+0.596 V) and the disproportionation of TcO₄²⁻ is plausible at present in spite of the moderate reductive atmosphere (−0.533 to +0.114 V) estimated from the observation (the existence of TcO₂ and the absence of NiMoO₄) by TEM and electron diffraction.