• Energy Research

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.

Biomass conversion via pyrolysis has been regarded as a promising solution for bio-oil production. Compared to fossil fuels, however, the pyrolysis bio-oils from biomass are corrosive and unstable due to relatively high oxygen content. Thus, an upgrading of bio-oil is required to reduce O component while improving stability in order to use it directly as fuel sources or in industrial processes for synthesizing chemicals. The catalytic hydrodeoxygenation (HDO) is considered as one of the promising methods for upgrading pyrolysis bio-oil. In this research, the HDO was studied for various catalysts (HZSM-5, metal, and metal-phosphide catalysts) to improve the quality of bio-oil produced by fast pyrolysis of Saccharina japonica (SJ) in a fluidized-bed reactor. The HDO processing was carried out in an autoclave at 350 °C and different initial pressures (3, 6, and 15 bar). During HDO, the oxygen species in the bio-oil was removed primarily via formation of CO2 and H2O. Among the gases produced through HDO, CO2 was observed to be most abundant. The C/O ratio of produced bio-oil increased when CoMoP/γ-Al2O3, Co/γ-Al2O3, Fe/γ-Al2O3, or HZSM-5 was used. The Co/γ-Al2O3 resulted in higher HDO performance than other catalysts. The bio-oil upgraded with Co/γ-Al2O3 showed high HHV (34.41 MJ/kg). With the use of catalysts, the kerosene-diesel fraction (carbon number C12–C14) was increased from 36.17 to 38.62–48.92 wt.%.

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.

Stirred tank reactors are most commonly used both in the laboratory and industry. Particularly for bioreactors, the volumetric mass transfer coefficient (kLa) of oxygen is used as one of the important parameters for determining efficiencies of reactors and for successful scale‐up. A number of correlation methods have been previously developed to predict the kLa in stirred tank bioreactors. In the present work, we propose a new correlation for kLa based on a mathematical and statistical approach using Response Surface Methodology (RSM) based on Box‐Behnken design of experiments. This correlation includes the effect of various parameters such as impeller agitation rate (50–800 rpm), air flow rate (0.5–3.5 L/min), and temperature (10−40°C) for different impeller configurations (single and dual Rushton, pitched blade, and mixed turbines). It was observed that the kLa increases with increasing the parameters for all the impeller configurations studied. Among the operating parameters, the most significant variable impacting kLa was found to be agitation rate, followed by air flow rate, and temperature. The models developed using RSM successfully interpreted the experimental kLa and were further validated under other operating conditions. It was also found that, compared with conventional power‐law models, the RSM approach enables a more efficient correlation procedure and formulates simplified models with comparably high accuracy, suggesting that the RSM is promising for evaluation of oxygen mass transfer in stirred tank bioreactors. © 2018 American Institute of Chemical Engineers Environ Prog, 38: 387–401, 2019