Tuan Amran Tuan Abdullah

Optimization and characterization of bio-oil produced by microwave assisted pyrolysis of oil palm shell waste biomass with microwave absorber

In this study, solid oil palm shell (OPS) waste biomass was subjected to microwave pyrolysis conditions with uniformly distributed coconut activated carbon (CAC) microwave absorber. The effects of CAC loading (wt%), microwave power (W) and N2 flow rate (LPM) were investigated on heating profile, bio-oil yield and its composition. Response surface methodology based on central composite design was used to study the significance of process parameters on bio-oil yield. The coefficient of determination (R(2)) for the bio-oil yield is 0.89017 indicating 89.017% of data variability is accounted to the model. The largest effect on bio-oil yield is from linear and quadratic terms of N2 flow rate. The phenol content in bio-oil is 32.24-58.09% GC-MS area. The bio-oil also contain 1,1-dimethyl hydrazine of 10.54-21.20% GC-MS area. The presence of phenol and 1,1-dimethyl hydrazine implies that the microwave pyrolysis of OPS with carbon absorber has the potential to produce valuable fuel products.

CO2 reforming of CH4 over Ni/mesostructured silica nanoparticles (Ni/MSN)

The development of supported Ni-based catalysts for CO2 reforming of CH4 was studied. Ni supported on mesostructured silica nanoparticles (MSN) and MCM-41 were successfully prepared using an in situ electrochemical method. The N2 physisorption results indicated that the introduction of Ni altered markedly the surface properties of MCM-41 and MSN. The TEM, H2-TPR and IR adsorbed CO studies suggested that most of the Ni deposited on the interparticles surface of MSN have higher reducibility than Ni plugged in the pores of MCM-41. Ni/MSN showed a higher conversion of CH4 at about 92.2% compared to 82.6% for Ni/MCM-41 at 750 °C. After 600 min of the reaction, Ni/MCM-41 started to deactivate due to the formation of shell-like carbon which may block the active sites and/or surface of catalyst, as proved by TEM analyses. Contrarily, the activity of Ni/MSN was sustained for 1800 min of the reaction. The high activity of Ni/MSN was resulted from the presence of greater number of easily reducible Ni on the surface. In addition, the large number of medium-basic sites in Ni/MSN was capable to avoid the formation of shell-like carbon that deactivated the catalyst, thus increased the stability performance. The results presented herein provide new perspectives on Ni-based catalysts, particularly in the potential of MSN as the support.

Hydrogen production from acetic acid steam reforming over bimetallic Ni-Co on La2O3 catalyst- Effect of the catalyst dilution

Catalytic steam reforming of acetic acid using bimetallic catalysts of 5 wt.% nickel and 5 wt.% cobalt supported on Lanthanum (III) oxide (La2O3) for hydrogen production was investigated in a micro fixed bed reactor. The reactor was of quartz tube with a 10 mm inside diameter. The effect of catalyst dilution on the reaction was studied. Silicon carbide was used as the dilution material. The experiments were conducted at atmospheric pressure and temperatures ranging from 500 to 700°C. The complete conversion of acetic acid to product gases has been observed at 550°C and 700°C for diluted and non-diluted catalysts respectively. It shows that catalyst dilution had a profound effect on the conversion of acetic acid at low temperature (550°C) whilst high temperature of 700°C was required for the non-diluted catalyst. The product gas distributions are similar when using both diluted and non-diluted catalysts.

Study on Dissolution of Low Density Polyethylene (LDPE)

The world is currently facing the problem brought by plastic waste, as well as energy crisis. It is known that catalytic cracking of low density polyethylene (LDPE) waste can produce liquid fuels with similar properties to fossil fuels, hence serve as a solution to the problems mentioned. However, the problem of pipelines clogging by molten plastic feed during the cracking process has to be solved before the process can be up-scaled to continuous process. It was proposed that LDPE waste can be dissolved in suitable solvent before being catalytically cracked under suitable conditions. This study was done to investigate the behavior of virgin LDPE (in powder form) dissolved in several chosen solvents, namely benzene, toluene, chlorobenzene, isooctane, xylene and trichloroethylene, and compare the result with previous work. From the study, it was observed that LDPE samples could dissolve in benzene and toluene to a high extent. On the other hand, isooctane acted as a weak solvent towards LDPE powder. The difference of LDPE solubility in solvents was attributed to the surface area per unit mass of LDPE samples. Despite the superior property of benzene as solvent for LDPE, the safety factor study showed that toluene, xylene and trichloroethylene were more suitable to be used in LDPE dissolution. However, care should be taken to minimize possible effects of the solvents towards the body while using the solvents mentioned.

Non-isothermal kinetic analysis of oil palm empty fruit bunch pellets by thermogravimetric analysis

The pyrolysis kinetics of oil palm empty fruit bunch (OPEFB) pellets was examined under non-isothermal conditions in a thermogravimetric (TG) analyser. Thermal analysis was carried out from 30 °C to 1,000 °C using three different heating rates 5, 10, 20 °C min -1 under nitrogen gas (N2). The TG-DTG curves showed that the pyrolysis process occurred in three steps; drying, active pyrolysis and passive pyrolysis signifying the removal of moisture, holocellulose and lignin. The pyrolysis kinetic parameters; activation energy, Ea, and frequency factor A, were deduced from the Flynn-Wall-Ozawa (FWO) model. The average Ea and A values from α = 0.10 0.60 were 160.20 kJ/mol and 1.38 x 10 24 min -1 . The highest Ea (231.42 kJ/mol) and A (8.27 x 10 24 min -1 ) occurred at α = 0.30 indicating this is the slowest or rate determining step (RDS) during thermal degradation of OPEFB pellets. The average Ea for OPEFB pellets was comparably lower than cornstalk (206.40 kJ/mol), sawdust (232.60 kJ/mol) and oak (236.20 kJ/mol). The kinetic compensation or isokinetic effect was also observed during thermal decomposition of the OPEFB pellets. Hence, the results indicate OPEFB pellets can be utilized as a potential feedstock for pyrolysis.

Modelling multicomponent devolatilization kinetics of imperata cylindrica

Biomass devolatilization is an important phenomenon in the thermochemical conversion of biomass into clean fuels through pyrolysis, gasification and combustion. In this paper multicomponent model fitting (MMF) was carried out to analyse the devolatilization kinetics of Imperata cylindrica using non-isothermal thermogravimetry (TG) to determine the pre-exponential factors (k0), activation energies (Ea) and fractional contribution. The TGA of Imperata cylindrica was carried out in the temperature range of 30-1,000 °C at four heating rates of 5, 10, 15, and 20 K/min using Nitrogen at a flow rate of 20 mL/min as purge gas. Evaluation of the kinetic parameters involved the numerical regression of the non-isothermal TGA data in MATLAB 2013a based on the pseudocomponent modelling method. The pseudocomponents number used in the modelling was limited between 3 and 10, and the overall quality of fit (QOF) for eight pseudocomponents was found to be the lowest with the value of 1.89 %. The corresponding average values for pre-exponential factor, activation energy and fractional contribution were 791.63 s -1 , 12.13 kJ/mol and 0.13. The results proved that pseudocomponent reaction modelling method can be successfully employed to accurately predict the experimental devolatilization rates.

Gasification of Empty Fruit Bunch Briquettes in a Fixed Bed Tubular Reactor for Hydrogen Production

The gasification of EFB briquette was investigated in a fixed bed tubular reactor to examine the effects of temperature on gas composition, heating value and cold conversion efficiency.The resultsrevealedthat H2 gas composition increased from 17.17 mol. % to 29.67 mol. % with increasing temperature from 600°C to 700°C at an equivalence ratio (ER) of 0.4. The heating value (HHV) of the producer gas increased from 6.18 MJ/Nm3 to 7.64 MJ/Nm3 and cold gas efficiency increased from 35.19% to 43.50% with increasing temperature during gasification. However, carbon conversion efficiency increased only marginally from 31.85% to 32.84% while a significant quantity of char (~ 21%) was produced per unit mass of EFB briquette. The results indicate that higher temperatures are required to increase the overall efficiency of EFB briquette gasification in a fixed bed tubular reactor.

Mathematical modeling of a single stage ultrasonically assisted distillation process.

The ability of sonication phenomena in facilitating separation of azeotropic mixtures presents a promising approach for the development of more intensified and efficient distillation systems than conventional ones. To expedite the much-needed development, a mathematical model of the system based on conservation principles, vapor-liquid equilibrium and sonochemistry was developed in this study. The model that was founded on a single stage vapor-liquid equilibrium system and enhanced with ultrasonic waves was coded using MATLAB simulator and validated with experimental data for ethanol-ethyl acetate mixture. The effects of both ultrasonic frequency and intensity on the relative volatility and azeotropic point were examined, and the optimal conditions were obtained using genetic algorithm. The experimental data validated the model with a reasonable accuracy. The results of this study revealed that the azeotropic point of the mixture can be totally eliminated with the right combination of sonication parameters and this can be utilized in facilitating design efforts towards establishing a workable ultrasonically intensified distillation system.

Pyrolysis of low density polyethylene waste in subcritical water optimized by response surface methodology

Pyrolysis of low density polyethylene (LDPE) waste from local waste separation company in subcritical water was conducted to investigate the effect of reaction time, temperature, as well as the mass ratio of water to polymer on the liquid yield. The data obtained from the study were used to optimize the liquid yield using response surface methodology. The range of reaction temperature used was 162–338°C, while the reaction time ranged from 37 min to 143 min, and the ratio of water to polymer ranged from 1.9 to 7.1. It was found that pyrolysis of LDPE waste in subcritical water produced hydrogen, methane, carbon monoxide and carbon dioxide, while the liquid product contained alkanes and alkenes with 10–50 carbons atoms, as well as heptadecanone, dichloroacetic acid and heptadecyl ester. The optimized conditions were 152.3°C, reaction time of 1.2 min and ratio of water solution to polymer of 32.7, with the optimum liquid yield of 13.6 wt% and gases yield of 2.6 wt%.

Process simulation for removing impurities from wastewater using sour water 2-strippers system via Aspen Hysys

Abstract In this paper, Aspen Hysys v8.8 was used to simulate two strippers for sour water stripping process as the aim for removal of chemical impurities such as hydrogen sulfide, carbon dioxide and ammonia in wastewater. As a result of elimination of these impurities, the water can be reused. Comparison between single and two strippers and elevating the stripping efficiency was the objectives of the present study. The feed flow rate and compositions were specified according to the typical Chevron WWT process conditions. The simulation result shows that 100 % ammonia was stripped into the two stripper system but only 24 % stripped in the single stripper system. The result of H2O was almost same in both systems. The stripped water collected via the bottom of the Ammonia Stripper contains less than 10 ppm of hydrogen sulphide and less than 50 ppm of ammonia.