Pious O Okekunle - Academia.edu (original) (raw)

Papers by Pious O Okekunle

IOP conference series, Apr 1, 2021

In this study, the physicochemical properties such as proximate, ultimate analysis and heating va... more In this study, the physicochemical properties such as proximate, ultimate analysis and heating value of five wood species sawdust (WSD) samples have been determined. The Higher Heating Values (HHVs) of the samples were estimated as functions of fixed carbon (FC) and volatile matter (VM), and were also calculated from an elemental composition-based correlation equation. Results showed the ranges of VM and FC were 74.95 – 75.74% and 14.25 – 14.80%, respectively. The High Heating Values (HHV) of Iroko, West African Entada, Ebony, African cam and Rough chaff, according to ultimate analysis-based correlation equation, were found to be 18.85, 18.77, 18.75, 18.55 and 18.52 MJ kg-1, respectively while according to proximate analysis-based correlation equation, were 18.41, 18.53, 18.43, 18.50 and 18.14 MJ kg-1. The high percentage of VM and the value range of FC resulted in appreciable HHVs for the samples. It can be concluded that woody biomass residues are good sources of bio-fuels for sustainable development.

Biofuels, Feb 9, 2017

Bio-oils from the fast pyrolysis of switchgrass forage and two sets of alfalfa stems (from two st... more Bio-oils from the fast pyrolysis of switchgrass forage and two sets of alfalfa stems (from two stages of developmentsbud and full flower stages) have been analyzed by wet-chemical methods, GC-MS, and HPLC. The chemical composition of bio-oil is important because it may give insights into its quality, stability, or suitability for downstream upgrading. Pyrolysis experiments were conducted at 500°C under a nitrogen atmosphere in 2.5 kg/h fluidized bed reactor. A total of 62 chemical species were positively identified in the liquids. Of the identified compounds, 27 have been quantified. The chemical compositions of the bio-oils are compared with what is known about the compositions of these feedstocks. While the compositions of the bio-oil from the two alfalfa stems were similar, there were numerous differences in the compositions of the alfalfa and switchgrass bio-oils. Noted are the higher levels of nitrogen, water, and aromatic hydrocarbons in bio-oils produced from alfalfa stems than from switchgrass and woody feedstocks that have been previously characterized. Also noted is a much lower concentration of levoglucosan and hydroxyacetaldehyde concentrations among bio-oils from alfalfa stems compared with bio-oil from switchgrass or woody biomass.

Case Studies in Chemical and Environmental Engineering, 2020

In this study, Ficus exasperata (Fe) leaf (sand paper leaf) raw sample was characterized using pr... more In this study, Ficus exasperata (Fe) leaf (sand paper leaf) raw sample was characterized using proximate and ultimate analysis and the ash was characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. XRF analysis showed that Alumina (Al 2 O 3) and Silica (SiO 2) were 6.50% and 67.50%, Energy Dispersive X-ray (EDX) analysis showed high presence of silica (42.40%), alumina (15.00%) and Oxygen (20.80%). FTIR unveiled peaks with zeolite-Y patterns. SEM analysis indicates good surface morphology and hexagonal shaped crystal lattice in comparison with commercial zeolite-Y.

IOP Conference Series: Materials Science and Engineering, 2018

In this study, pyrolysis of sawdust sample (Western blood-wood-Eucalyptus terminalis) was investi... more In this study, pyrolysis of sawdust sample (Western blood-wood-Eucalyptus terminalis) was investigated. Experiments were performed at six temperature levels ranging from 300 o C to 800 o C under N2 atmosphere. The weights of char, tar and gas yields produced in each experiment were measured and recorded in percentage of initial weight of the pyrolyzed sample. Results of the study showed that product yield of Eucalyptus terminalis char, tar and gas of 41.28% at 300 o C, 45.10% at 300 o C and 57.20% at 800 o C, respectively were produced. Proximate analysis shows that volatile matter, fixed carbon, ash content and moisture content of sawdust sample were 75.53%, 15.35%, 1.56% and 7.56%, respectively. Result of the elemental analysis shows that the carbon, hydrogen, nitrogen, oxygen and sulphur contents of the sawdust sample were 54.19%, 7.05%, 0.97%, 37.15%, and 0.64%, respectively. The higher heating value and pH of the sawdust sample are 23.40 kJ/g and 2.30% respectively. This indicate that char and tar yields decrease with increased pyrolysis temperature while gas yield increases as pyrolysis temperature increases for the sawdust sample. The value of the correlation coefficient obtained indicate a fairly high degree of accuracy of the regression models to predict experimental result when used within the temperature range considered in this study. Result of analytical Py-GC/MS shows that the proportion of phenolic compounds identified was more than 50% with trans-2-octadecadecen-1-ol, cis-10-pentadecen-1-ol, 9octadecenal and methyl-1-cyclohexenyl ketone dominating. This study establishes the fact that pyro-oil can not only be used as a fuel but can also be purified and serves as raw materials for chemical and processing industries.

In this research work, the product yield distribution from four different sample shapes of a biom... more In this research work, the product yield distribution from four different sample shapes of a biomass feedstock (Gmelina arborea) was investigated. The biomass feedstock (Gmelina arborea) was procured from Pakiotan Sawmill in Ogbomoso, South-Western Nigeria. The biomass feedstock was machined into four different shapes (rectangular, cylindrical, disc and equant) of equal volume of 22.8 cm3 on the wood Lathe machine at the Engineering Workshop of Ladoke Akintola University of Technology (LAUTECH), Ogbomoso, Nigeria. Experiments were carried out at four different temperatures (400, 500, 600 and 700 oC) at a residence time of fifteen minutes and at a constant vacuum pressure using a fixed-bed reactor. Results obtained showed that tar yield was 3.66 % at 700 oC and 18.15 % at 400 oC for cylindrical shape, and 7.5 % at 700oC and 25.04 % at 400 oC for disc shape. From the experimental data, it was also observed that the cylindrical shape has the highest gas yield of 80.11 % at a temperatur...

In this study, a coupled transport and chemical kinetic model was used to simulate the effects of... more In this study, a coupled transport and chemical kinetic model was used to simulate the effects of biomass thermo-physical properties on intra-particle secondary reactions during convective-radiative pyrolysis of wood cylinder ( ⁄ in a thermally thick regime. Wood cylinder was modeled as a one-dimensional porous solid. Solid mass conservation equations were solved by first-order Euler Implicit Method. Finite volume method was used to discretize the mass conservation equation for tar and gas, the energy conservation equation and the pressure equation. Tri-Diagonal Matrix Algorithm (TDMA) was used to solve the resulting simultaneous equations. Findings revealed that thermo-physical properties influence the extent of intra-particle secondary reactions, biomass conversion time and product yield distribution. Simulation results also showed that density has the highest influence on intra-particle secondary reactions.

Effect of reactor peak temperature on biomass pyrolysis in thermally thick regime with a constant... more Effect of reactor peak temperature on biomass pyrolysis in thermally thick regime with a constant heating rate of 30 K/s, reactor pressure of 1 atm and reactor peak temperature ranging from 500 to 1000 oC in a fixed-bed reactor has been numerically investigated. Wood cylinders ( = 400 ⁄ , ∅ 10 and length 20 ) were modeled as two-dimensional porous solids. Transport equations, solid mass conservation equations, intra-particle pressure generation equation and energy conservation equation were coupled and simultaneously solved to simulate the pyrolysis process. First order Euler Implicit Method (EIM) was used to solve the solid mass conservation equations. The transport, energy conservation and intra-particle pressure generation equations were discretized by Finite Volume Method (FVM). The generated set of linear equations was solved by Tri-Diagonal Matrix Algorithm (TDMA). Intra-particle fluid flow velocity was estimated by Darcy’s law. Results showed that increase in reactor temperat...

Combined effects of reactor pressure (0.0001, 0.01, 1, 10, 100 atm) and heating rate (10, 20, 30,... more Combined effects of reactor pressure (0.0001, 0.01, 1, 10, 100 atm) and heating rate (10, 20, 30, 40 and 50 K/s) on biomass pyrolysis characteristics at a final reactor temperature of 973 K in thermally thin regime have been numerically investigated. Wood pellets (= 400 ⁄ , ∅ 1 and length 1) were modeled as twodimensional porous solids. Transport equations, solid mass conservation equations, intra-particle pressure generation equation and energy conservation equation were coupled and simultaneously solved to simulate pyrolysis. Solid mass conservation equations were solved by first order Euler Implicit Method (EIM). Finite Volume Method (FVM) was used to discretize the transport, energy conservation and pressure generation equations, and the resulting linear simultaneous equations were solved by Tri-Diagonal Matrix Algorithm (TDMA). Intra-particle fluid flow velocity was estimated by Darcy's law. Results showed that pressure does not have any significant effect on biomass primary disintegration reactions at all heating rates. Increase in heating rate accelerated the rate of biomass primary conversion. In the vacuum region, increase in pressure did not have any significant effect on tar, gas and secondary tar release rates and yields at all heating rates. Increase in pressure from vacuum to atmospheric, and from atmospheric to pressurized condition diminished tar release rate and yield but favoured gas and secondary tar release rates and yields at all heating rates. Findings further showed that volatiles intra-particle secondary reactions products generation rates at atmospheric and pressurized conditions were ten times and over higher than those at vacuum conditions. It was concluded that at and above atmospheric pressure conditions, pressure can significantly influence the rate of generation, yield and percentage composition of product species.

Journal of Energy Technologies and Policy, 2018

The influence of operating parameters on the product yields during the pyrolysis of Oil Palm Husk... more The influence of operating parameters on the product yields during the pyrolysis of Oil Palm Husk (OPH) was investigated in this study. 0.5 kg of dried sample of OPH was loaded into a steel retort, and the retort interior was rendered airtight. The retort was then placed into the furnace chamber and the OPH was pyrolysed at 300 o C between 10 - 30 minutes at 5 minutes interval. This was repeated for temperatures of 400, 500, 600 and 700 o C and in each case, the quantities of char, tar and pyro - gas produced were determined. Response surface methodology (RSM) was used to develop polynomial regression model and investigate the effect of changes in the level of pyrolysing temperature and duration on the product yields using Full Factorial Design (FFD). The contribution of pyrolysis temperature, duration and their squares (A, B, A 2 and B 2 ) to the model developed are significant model terms. It was observed that the experimental data fitted better because of the Pred R-Squared of 0...

This work investigated the effect of different oven drying and furnace temperatures on product yi... more This work investigated the effect of different oven drying and furnace temperatures on product yield distribution of rice husk pyrolysis. Rice husk was procured from a rice milling plant in Ogbomoso, South-Western Nigeria and was sundried for 3 days, and then oven dried at different temperatures (60, 75, 90, 105 and 120 ⁰C) for 30 minutes in Chemical Engineering Laboratory, Ladoke Akintola University of Technology, Ogbomoso, Nigeria. The samples were then pyrolysed at different reactor temperatures (400, 500, 600 and 700 °C) with a residence time of 25 minutes. The retort was inserted into the furnace after being fed with the sample. For each run, the reactor temperature was set to be 100 o C higher than the desired temperature in order to compensate for heat loss during retort insertion. Moisture loss was in the range 5.58% (at 60 o C drying temperature) to 9.03% (at 120 o C drying temperature). The yields of tar, gas and char were then obtained after pyrolysis and expressed in per...

International Journal of Research, 2018

The need to convert waste to wealth for sustainable development cannot be overemphasized. In this... more The need to convert waste to wealth for sustainable development cannot be overemphasized. In this work, effect of reactor temperature on product yields from pyrolysis of African Oak ( Oldfieldia africana ) sawdust in a fixed bed reactor was investigated. Sawdust sample was obtained from Paki-Otan sawmill,Ogbomoso, Oyo state, Nigeria. The sample was sundried for three days and then oven dried at 104 o C for 2 hours in order to reduce its moisture content. Samples of 50 g each were pyrolysed at different temperatures (300, 400, 500 and 600 o C) for 15 minutes at atmospheric pressure. Results showed that char yield decreased while gas yield increased as reactor temperature increased. Tar (bio-oil) yield increased with temperature up to 500 o C and then decreased with further increase in temperature. Secondary pyrolysis became significant above 500 o C. The ranges of char, bio-oil and gas yields were 22.70 – 47.50%, 32.30 – 41.80% and 20.20 – 38.20%, respectively. Sawdust from wood pro...

Nigerian Journal of Technological Research, 2018

The quest for energy generation in the most environmentally friendly way has necessitated the con... more The quest for energy generation in the most environmentally friendly way has necessitated the conversion of agricultural residues, believed to constitute nuisance to the environment, into useful bio-fuels. Pyrolysis of West African Cordia (Cordia millenii) sawdust was carried out in a purposely built tubular carbon steel reactor under N 2 atmosphere within the temperature range of 410 and 530 o C. Proximate and elemental analyses were also performed on the raw sample using iso-conversional methods. Product yields were collected at 30 o C interval. Bio-oil yield was characterized by using analytical Py-GC/MS technique. The Higher Heating Value (HHV) of the sample was found by using Parr bomb calorimeter while that of char yield was theoretically determined. The highest yield of pyro-oil was 63.4% at 500 oC, that of pyro-gas was 30% at 500 o C and that of char was 35% at 410 oC. The proportion of phenolic compounds identified was more than 75% with trans-2octadecadecen-1-ol, cis-10-pentadecen-1-ol, 9-octadecenal, methyl-1-cyclohexenyl ketone showing dominance. The HHV of the raw sample and char yield were 18.07 and 18.95 MJ/kg, respectively.

Uludağ University Journal of The Faculty of Engineering

This study analyzed the fuel properties of bio-oils produced by catalytic fast pyrolysis of Tecto... more This study analyzed the fuel properties of bio-oils produced by catalytic fast pyrolysis of Tectona grandis in a fixed bed reactor at different temperatures (400-600 o C) and biomass to catalyst (b/c) weight ratios (90/10-60/40). Magnesium oxide (MgO) was used as catalyst. The product yields were determined. Bio-oils were characterized with their elemental composition and their Higher Heating Values (HHVs) as well as their basic fuel properties at maximum bio-oil yields conditions, including viscosity, flash point, moisture content, pH value and Conradson Carbon Residue (CCR), were determined and compared with those of non-catalytic pyrolysis bio-oils. The maximum yields of bio-oil at 400, 500 and 600 o C were 31.53, 40.87 and 29.30 wt.%, respectively, obtained at b/c ratios of 70/30, 80/20 and 70/30. Catalytic pyrolysis bio-oils possessed higher carbon and hydrogen but lower oxygen and sulphur contents than non-catalytic pyrolysis bio-oils. The HHVs of catalytic pyrolysis bio-oils (40.31-42.08 MJ/kg) were higher than those of non-catalytic bio-oils (36.47-36.76 MJ/kg). Catalyst reduced the viscosity (at 400 and 500 o C), moisture content and CCR (at 400 and 600 o C), and increased the pH value of bio-oils (at 400 and 600 o C). Catalytic pyrolysis deoxygenates and enhances the fuel properties of bio-oils.

International Journal of Energy for a Clean Environment

FUOYE Journal of Engineering and Technology

The effect of potassium carbonate catalyst on the products distribution from pyrolysis of Milicia... more The effect of potassium carbonate catalyst on the products distribution from pyrolysis of Milicia excelsa (Iroko) at various temperatures (400, 500 and 600 oC) was investigated. Milicia excelsa sawdust was obtained from a sawmill in Ogbomoso, South-Western Nigeria and was sundried for five days in order to reduce its moisture content. Catalytic pyrolysis of the sawdust was performed with different amounts of catalyst (10, 20, 30 and 40 wt.%). Non-catalytic pyrolysis was also performed for the same temperatures and the products distributions from both batches were compared. Char yield generally increased with increase in catalyst amount for all the temperatures considered. Tar yield did not follow any definite pattern with increasing amount of catalyst as different trends were obtained for different temperatures. Gas yield generally decreased with increase in catalyst amount in the feed. Char yields from non-catalytic experiments were higher than those obtained from catalytic runs, w...