Oil Palm Stone Research Articles

Combustion of oil palm stone in a pilot-scale fluidised bed reactor

Biomass is being generated in vast amounts from oil palm plantations particularly in developing countries such as Malaysia, Thailand and Indonesia. Oil palm stone (OPS) is currently considered a waste material and has not previously been considered for energy purposes. The main objective of this study was to investigate the thermochemical conversion of OPS in a pilot-scale fluidised bed combustor. The net heating value of OPS was 24.93 MJ/kg. The effect of primary air flowrate and initial bed temperature were the main parameters investigated. The bed and bed's surface temperature were found to decrease as the primary air flowrate increased. In all tests CO emissions were less than 0.2%. The emissions of SO 2 and HCl ranged from 0.02 ppm to 0.05 ppm, significantly below the permitted levels set by legislation. Stable combustion was observed at a bed temperature of 950 °C. The most abundant elements found in the ash were Al, Ca, Fe, K, Mg, Mn, P, S and Si. However, due to the temperature regime used in the study fouling would not be an issue.

Pyrolysis and combustion of oil palm stone and palm kernel cake in fixed-bed reactors

The main objective of this research was to investigate the main characteristics of the thermo-chemical conversion of oil palm stone (OPS) and palm kernel cake (PKC). A series of combustion and pyrolysis tests were carried out in two fixed-bed reactors. The effects of heating rate at the temperature of 700°C on the yields and properties of the pyrolysis products were investigated. The results from the combustion experiments showed that the burning rates increased with an increase in the air flow rate. In addition, the FLIC code was used to simulate the combustion of the oil palm stone to investigate the effect of primary air flow on the combustion process. The FLIC modelling results were in good agreement with the experimental data in terms of predicting the temperature profiles along the bed height and the composition of the flue gases.

Activated carbon prepared from oil palm stone by one-step CO 2 activation for gaseous pollutant removal

Activated carbon prepared from oil palm stone by one-step CO 2 activation for gaseous pollutant removal

Preparation and characterization of activated carbons from oil-palm stones for gas-phase adsorption

Preparation and characterization of activated carbons from oil-palm stones by carbon dioxide activation were studied in this paper. These oil-palm stones are agricultural by-products from palm-oil mills in several tropical countries. Ultimate and proximate analyses, pycnometry, mercury porosimetry, surface area and porosimetry as well as transmission electron microscopy were carried out for evaluating the textural properties of the activated carbons. It was found that the activation temperature and hold time had significant influences on the surface area and pore size distribution of the activated carbon. The optimum conditions for preparing these activated carbons from chars pyrolyzed at 600°C to derive the highest specific surface areas were found to be an activation temperature of 900°C and a hold time of 30 min. For chemical characterization, an X-ray diffractometer and a Fourier transform infrared (FTIR) spectroscope were used to identify the inorganic components and surface organic functional groups of the activated carbons, respectively. The activation temperature and hold time had significant effects on the surface functional groups. For the determination of the adsorptive capacity of the activated carbons, adsorption of sulphur dioxide was carried out using thermogravimetric analyses. Experimental results showed that sulphur dioxide could be adsorbed effectively by the oil-palm stone-activated carbons. The adsorptive capacity of these activated carbons was comparable with those of some commercial activated carbons.

Activated carbon prepared from oil palm stone by one-step CO2 activation for gaseous pollutant removal

Abstract The feasibility of preparing activated carbons from oil palm stones by one-step CO2 activation was studied. These oil palm stones are major solid wastes generated from palm-oil processing mills. Experimental results showed that the particle size of the starting material and heating rate appeared to have no significant effects on the BET surface areas of the activated carbons but CO2 flow-rate had a significant influence. Increasing the heating rate resulted in slight reductions in the micropore surface areas. The BET and micropore surface areas of the activated carbons were also found to be dependent on the activation temperature and the hold time. The optimum conditions for activation were for an activation temperature of 850°C and a hold time of 2 h, at which the BET and micropore surface areas were found to be maximum at 1410 and 942 m2 g−1 respectively. The pore size distributions of the activated carbon also confirmed these conditions. The development of microporosities in these activated carbons suggest their potential applications in gaseous pollutant adsorption. From chemical characterisation, the activation temperature was found to have an insignificant effect on the inorganic components of the activated carbons but possible effects on their surface functional groups. The amounts of NO2 adsorbed onto the oil-palm-stone activated carbons and a commercial one were measured during adsorption tests. The relationship between the amount of gas adsorbed and the BET surface area of the activated carbon indicated that the adsorptive capacity was linearly proportional to the surface area.

Effect of Heating Temperature on the Properties of Chars and Activated Carbons Prepared From Oil Palm Stones

The effects of heating temperature of pyrolysis and activation processes on the textural and chemical properties of the chars and activated carbons prepared from oil palm stones, an abundant palm-oil mill solid waste, were studied. For both pyrolysis and activation, relatively high temperature was essential to develop pore structures in the chars and activated carbons. However, too high temperature would cause pore narrowing and pore enlargement during pyrolysis and activation, respectively. The temperature had an insignificant effect on the inorganic components of the chars and activated carbons, but affected their surface organic functional groups significantly.

Textural Characterization of Activated Carbons Prepared from Oil-palm Stones Pre-treated with Various Impregnating Agents

Activated carbons with relatively high densities and well-developed porosities were prepared from oil-palm stones which were pre-treated with different types of impregnating agents (ZnCl2, H3PO4 or KOH). The benefits derived from impregnation in terms of higher BET surface areas were generally in the following order: 20% ZnCl2 > 40% H3PO4 > 10% KOH. The textural properties such as density and total porosity, overall yield, BET and micropore surface areas and pore size distributions of the activated carbon were related to the concentration of the impregnating solution and the activation conditions (activation temperature and hold time). For the highest BET surface area obtained in this study, the optimum conditions for CO2 activation were found to be at an activation temperature of 750°C for 1 hour from oil-palm stones pre-treated with 20% ZnCl2 for 24 hours. Pore size distribution suggests the application of oil-palm-stone activated carbons as gas-phase adsorbents for air pollution control.

Textural and chemical characterisations of activated carbon prepared from oil-palm stone with H 2SO 4 and KOH impregnation

Textural and chemical characterisations of the activated carbon prepared from oil-palm stone, an abundant tropical solid waste, by pre-treatment with H 2SO 4 and KOH impregnation were carried out in this study. The effects of impregnations concentration and soaking time on the textural properties, such as adsorption isotherm, porosity, surface area and pore size distribution were investigated. A reasonably high BET surface area and predominant microporosity of the oil-palm stone carbons suggested their potential applications in gas-adsorbing processes. From adsorption tests of SO 2 and NH 3, it was found that the activated carbons pre-treated with KOH could adsorb more SO 2 but less NH 3 than those pre-treated with H 2SO 4, even though they had almost identical BET and micropore surface areas. This indicated that the adsorptive capacity of the activated carbon was not only determined by its textural characteristics, but also related to the surface chemistry. Chemical characterisation showed that impregnation affected significantly the surface chemistry, i.e. inorganic component and surface organic functional group. For organic functional groups, the samples pre-treated with H 2SO 4 presented acidic groups such as phenols and carboxylic acids, whereas those with KOH impregnation showed alkaline groups suggested to be pyrones (cyclic ketone) and other keto-derivatives of pyran. In general, the activated carbons prepared from oil-palm stones with impregnation of KOH and H 2SO 4 are suitable for use as gas-phase adsorbents for the removal of acidic and alkaline gases, respectively.

Effect of surface chemistry on gas-phase adsorption by activated carbon prepared from oil-palm stone with pre-impregnation

Effects of surface chemistry (acidity or basicity) on gas-phase adsorption (NO2 or NH3) by activated carbons prepared from oil-palm stones pre-impregnated with various solutions (ZnCl2, H3PO4 and KOH) were studied in this paper. Textural and chemical characterizations of these activated carbons were carried out. High solid density and hardness, fairly high BET surface area and predominant microporosity (as shown in the pore size distributions) of the oil-palm-stone activated carbons suggested their potential applications in gas-adsorbing processes. Chemical characterization showed that impregnation affected significantly the surface chemistry, i.e. surface functional group. The samples pre-treated with H3PO4 presented acidic groups such as phenols and carboxylic acids, whereas those with KOH impregnation showed basic groups likely to be pyrones (cyclic ketone) and other keto-derivatives of pyran. From adsorption tests of NO2 and NH3, it was found that the activated carbons pre-treated with KOH could adsorb more NO2 but less NH3 than those pre-treated with H3PO4, even though they had almost identical BET surface areas. This indicated that the adsorptive capacity of the activated carbon was not only determined by its textural characteristics, but also related to the surface chemistry, which was relevant to the type of impregnating agent, concentration of impregnation solution and activation temperature. In general, the activated carbons prepared from oil-palm stones impregnated with H3PO4 and KOH are suitable for adsorbing basic (NH3) and acidic (NO2) gases, respectively.

Characterization of chars pyrolyzed from oil palm stones for the preparation of activated carbons

Chars pyrolyzed from oil palm stones, an abundant palm-oil mill solid waste, for the preparation of activated carbons were characterized in this paper. An ultra-pycnometer and a mercury intrusion porosimeter were used to measure the solid and apparent densities of the samples, respectively and a thermogravimetric analyzer was used for proximate analysis. The effects of pyrolysis temperature and retention time on the char yield and BET surface area of the chars were investigated. The optimum condition for pyrolysis was found to be at a pyrolysis temperature of 800°C for a retention time of 3 h. The SEM micrographs of the char surfaces verified the presence of porosity. The experimental results showed that it was feasible to prepare chars with sufficient densities and relatively high porosities from oil palm stones for the further preparation of activated carbons.