• Energy Research

Abstract Spent coffee waste (SCW) is extremely attractive to be exploited and utilized as a material source for energy generation and chemical production. This study concerned bio-oil production via non-catalytic and catalytic fast pyrolysis using SCW in a bubbling fluidized-bed reactor (BFR). In particular, a comparative analysis of the quality of the bio-oil produced was conducted for non-catalytic (using silica sand as the bed material) and catalytic (using dolomite, HZSM-5, hematite, and magnetite as the catalyst) fast pyrolysis. Scale-up modeling confirmed using the experimental data was performed at a feed rate of 100 kg h−1 (1,000-fold capacity), which showed different orders in the quality of energy (hematite > magnetite > dolomite > HZSM-5 > silica, in order of energy from highest to lowest) owing to the realistic integration of the BFR with other components in plants, such as the combustor, compressor, and separator. Further, techno-economic analysis of scale-up system revealed that the unit production costs of bio-oil were 0.0151, 0.0034, 0.0143, 0.0095, and 0.0102 $ MJ−1 for silica, dolomite, HZSM-5, hematite, and magnetite, respectively (dolomite > hematite > magnetite > HZSM-5 > silica, in order of unit cost from lowest to highest). Among them, dolomite and hematite showed competitive unit production costs compared to the price of conventional crude oil (0.0098 $ MJ−1). The importance of coupling laboratory-scale experimental results with scale-up modeling and economic analysis has thus been demonstrated for practical feasibility studies of the SCW pyrolysis for bio-oil production.

Abstract Oil palm empty fruit bunch (EFB) contains the inorganic materials such as K, Na, Mg, and Ca, which cause some problems during fast pyrolysis reaction. In this paper, we report the effect of pretreatment by acid washing with dilute nitric acid to both remove the inorganic materials and increase the bio-oil production at fast pyrolysis in a bubbling fluidized-bed reactor. By pretreating dilute nitric acid at EFB, the total liquid yield enhancement was from 52.2 wt% to 63.9 wt% and the char yield reduction was from 39.9 wt% to 41.9 wt% compared to original EFB. Using various analytical tools including elemental analysis, thermogravimetric analysis, inductively coupled plasma atomic emission spectroscopy, pH meter, Karl-Fischer titration, gas chromatography, gas chromatography-mass spectrometry, and 13C nuclear magnetic resonance, the properties and components of bio-oil in original EFB and acid-washed EFB samples were investigated. Through analytical tools, the biomass and bio-oil both in original and acid-washed EFB were analyzed to obtain various properties such as compositions, higher heating value, product yield, 13C NMR spectra, and carbon number.

Abstract Bamboo has been considered a potential feedstock of energy for the future. It can be subjected to the pyrolysis for biofuels production. The thermogravimetric analysis (TGA) combined with differential thermogravimetric analysis (DTG) for bamboo was carried out prior to pyrolysis. The thermal degradation of bamboo was mainly between 230 and 420 °C. The conventional pyrolysis of bamboo was investigated in a bubbling fluidized-bed reactor using silica sand. The product distribution and composition of pyrolysis bio-oil were dependent on biomass component and operating conditions such as pyrolysis temperature, fluidization velocity, and particle size of biomass. The fractional catalytic pyrolysis of bamboo was also studied to upgrade the pyrolysis vapor, using HZSM-5 and red mud. The highest yield of bio-oil was 54.03 wt% compared to 49.14 wt% and 50.34 wt% of HZSM-5 and red mud catalyst, respectively. In the red mud catalytic pyrolysis, the oxygen content was rejected from pyrolysis vapor mostly via decarboxylation to produce more CO2 than CO; in contrast, for the HZSM-5 catalytic pyrolysis, the production of CO through decarbonylation was more favored than CO2. The main composition of catalytic pyrolysis bio-oil was 4-vinylphenol, which was employed as a raw material source to synthesize valuable material for energy storage.

Abstract Cellulose accounts for the largest proportion of lignocellulosic biomass. Herein, experimental and simulation studies are used to deeply understand the kinetic characteristics of the thermal decomposition of α-cellulose. The simulated data is in good agreement with the experimental data in the aspects of the conversion and the conversion rate versus temperature. The decomposition of α-cellulose, mainly occurring at 270–420 °C, induced an apparent activation energy ranging from 175.42 kJ/mol to 197.73 kJ/mol at a conversion of 10–90%. With 0.1–0.2 wt% K or Ca impregnation into the α-cellulose, the mean activation energy for pyrolysis was lowered (from 181.47 kJ/mol (for α-cellulose) to 141.11 kJ/mol (for 0.2 wt% K/α-cellulose) and 159.46 kJ/mol (for 0.1 wt% Ca/α-cellulose)) and higher amounts of liquid and gas products were produced. Furthermore, the addition of potassium and calcium increased the production of lower molecular weight components, such as furfural and its derivatives. The kinetic parameters of the α-cellulose pyrolysis were determined based on a nonlinear least-squares regression of the experimental data assuming first-order kinetics and correlated with the simulated result. The kinetic rate constants indicate that the predominant reaction pathway is from α-cellulose into a liquid product, rather than from α-cellulose into a gas product.