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Lahijani P.,Universiti Sains Malaysia | Zainal Z.A.,Universiti Sains Malaysia | Mohamed A.R.,Universiti Sains Malaysia | Mohammadi M.,Noushirvani University of Technology
Bioresource Technology | Year: 2013

Palm empty fruit bunch ash (EFB-ash) was used as a natural catalyst, rich in potassium to enhance the CO2 gasification reactivity of palm shell char (PS-char). Various EFB-ash loadings (ranging from 0 to 12.5wt.%) were implemented to improve the reactivity of PS-char during CO2 gasification studies using thermogravimetric analysis. The achieved results explored that the highest gasification reactivity was devoted to 10% EFB-ash loaded char. The SEM-EDS and XRD analyses further confirmed the successful loading of EFB-ash on PS-char which contributed to promoting the gasification reactivity of char. Random pore model was applied to determine the kinetic parameters in catalytic gasification of char at various temperatures of 800-900°C. The dependence of char reaction rate on gasification temperature resulted in a straight line in Arrhenius-type plot, from which the activation energy of 158.75kJ/mol was obtained for the catalytic char gasification. © 2012 Elsevier Ltd. Source


Lahijani P.,Universiti Sains Malaysia | Zainal Z.A.,Universiti Sains Malaysia | Mohamed A.R.,Universiti Sains Malaysia | Mohammadi M.,Noushirvani University of Technology
Bioresource Technology | Year: 2013

This study investigates the influence of alkali (Na, K), alkaline earth (Ca, Mg) and transition (Fe) metal nitrates on CO2 gasification reactivity of pistachio nut shell (PNS) char. The preliminary gasification experiments were performed in thermogravimetric analyzer (TGA) and the results showed considerable improvement in carbon conversion; Na-char>Ca-char>Fe-char>K-char>Mg-char>raw char. Based on TGA studies, NaNO3 (with loadings of 3-7wt%) was selected as the superior catalyst for further gasification studies in bench-scale reactor; the highest reactivity was devoted to 5wt% Na loaded char. The data acquired for gasification rate of catalyzed char were fitted with several kinetic models, among which, random pore model was adopted as the best model. Based on obtained gasification rate constant and using the Arrhenius plot, activation energy of 5wt% Na loaded char was calculated as 151.46kJ/mol which was 53kJ/mol lower than that of un-catalyzed char. © 2013 Elsevier Ltd. Source


Lahijani P.,Universiti Sains Malaysia | Zainal Z.A.,Universiti Sains Malaysia | Mohamed A.R.,Universiti Sains Malaysia | Mohammadi M.,Noushirvani University of Technology
Bioresource Technology | Year: 2013

In this investigation, palm empty fruit bunch (EFB) and almond shell (AS) were implemented as two natural catalysts rich in alkali metals, especially potassium, to enhance the reactivity of tire-char through co-gasification process. Co-gasification experiments were conducted at several blending ratios using isothermal Thermogravimetric analysis (TGA) under CO2. The pronounced effect of inherent alkali content of biomass-chars on promoting the reactivity of tire-char was proven when acid-treated biomass-chars did not exert any catalytic effect on improving the reactivity of tire-char in co-gasification experiments. In kinetic studies of the co-gasified samples in chemically-controlled regime, modified random pore model (M-RPM) was adopted to describe the reactive behavior of the tire-char/biomass-char blends. By virtue of the catalytic effect of biomass, the activation energy for tire-char gasification was lowered from 250kJ/mol in pure form 203 to 187kJ/mol for AS-char and EFB-char co-gasified samples, respectively. © 2013 Elsevier Ltd. Source


Anisheh S.M.,Noushirvani University of Technology | Hassanpour H.,Shahrood University of Technology
International Journal of Electronics | Year: 2011

Signal analysis tools such as Fourier transform are often applicable on data with a limited length. Segmentation is an important pre-processing step in many signal processing applications. Statistical characteristics of the signal in a segment are often preferred to be similar. This characteristic, stationarity, improves performance of signal analysis technique. This article develops an adaptive segmentation method based on wavelet transform and fractal dimension from two aspects. One is to use discrete stationary wavelet transform in pre-processing step instead of using classical wavelet transform. The other is to choose the optimal parameters. Two parameters are needed to calculate the fractal dimension of a decomposed signal, window length and percentage overlapping of the successive windows, which affect the performance of the proposed approach. These parameters are optimally set using the particle swarm optimisation algorithm. Performance of the proposed method is compared with three other existing segmentation methods using both synthetic signal and real data. The results indicate the superiority of the proposed technique in terms of accuracy compared to existing methods. © 2011 Taylor & Francis. Source


Mohamed A.R.,Universiti Sains Malaysia | Mohammadi M.,Noushirvani University of Technology | Darzi G.N.,Noushirvani University of Technology
Renewable and Sustainable Energy Reviews | Year: 2010

A literature review on preparation of carbon molecular sieve (CMS) from lignocellulosic biomass is presented. The effect of various operation parameters such as pyrolytic temperature, flow rate of the carbonizing agent and time of pyrolysis on the carbonization of the lignocellulosic biomass as a carbon precursor was reviewed. Various physical and chemical processes for the activation of the biomass-based char and their effects on textural properties of the activated char were discussed. Conversion of activated chars to CMS as the final stage of the preparation process through different techniques of chemical vapor deposition (CVD) and controlled pyrolysis was assessed. Survey of literature revealed that production of CMS with BET surface area of 1247 m2/g and micropore volume of 0.51 cm3/g, under appropriate conditions has been reported. Also, maximum selectivity of 7.6 and 400 for separation of O2/N2 and CO2/CH4 was devoted to palm shell and coconut shell-based CMS, respectively. © 2010 Elsevier Ltd. All rights reserved. Source

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