Production of activated carbon from fast pyrolysis biochar and the detoxification of pyrolytic sugars for ethanol fermentation

Abstract

Fast pyrolysis of red oak wood yields approximately 10-30 wt% biochar, considered a low value co-product. Production of high value activated carbon using steam was investigated at different activation conditions. The relationship between activation parameters, surface area, and revenue was evaluated using response surface methodology. A second-degree model showed a maximum economic benefit at 800°C with 5 minutes of steam activation, yielding $907 of net revenue per metric ton of biochar. Innovation Fast pyrolysis, a thermochemical process that yields bio-oil as its primary product, is developing rapidly as a mean of producing advanced biofuels and other bio-based products. Coproducts include non-condensable gases and a carbon-rich solid residue known as char (or biochar when incorporated into the soil). Biochar, representing 10-30 wt% of the products, is currently a relatively low value agricultural soil amendment with an estimated wholesale value around $100 per ton 10. Thus, it is priced no higher than its precursor biomass. Developing additional, value-added applications for the biochar produced during fast pyrolysis would enhance the overall economic viability of fast pyrolysis technologies. One approach to developing such biochar products is upgrading the biochar to high value activated carbon (AC) with high surface area and porosity. Highlights  Fermentation of pyrolytic sugars into ethanol significantly improves the IRR of the fast pyrolysis biorefinery.  Activated carbon improves the overall economic feasibility by producing a high value product from the biochar stream.  The biorefinery requires $414 million in investment, primarily driven by the cost of hydroprocessing and combustion equipment.  The expected IRR of this biorefinery is 16% being the biomass cost and fixed capital investment the factors with higher impact on profitability.

Production of bioadsorbent from phosphoric acid pretreated palm kernel shell and coconut shell by two-stage continuous physical activation via N 2 and air

“…The physico-chemical characteristics and potential uses of adsorbent are greatly influenced by the biomass feedstock, feedstock pretreatments, carbonization method and activating conditions, such as temperature, gas type and reaction time [62]. Table 4 presents the contents of carbon, hydrogen, nitrogen, oxygen and ash content of the bioadsorbent.…”

The influence of pilot-scale pyro-gasification and activation conditions on porosity development in activated biochars

“…Abundant literature have examined the influence of activation parameters (e.g., activation temperature, activation time, gas flow rate, impregnation chemical, biochar ratio) on porosity development in activated biochars [24]. The results show that processing conditions at high activation temperature (e.g., 900 °C) [25][26][27][28][29][30][31], high CO2 or steam flow rate [32,33], longer residence time (e.g., 2h) [25,26,32,[34][35][36][37], and high chemical impregnation ratio [38][39][40] produce highly porous materials. However, little attention has been paid to the different pyro-gasification (i.e., an integrative term that comprises all thermochemical processes such as torrefaction, slow to fast pyrolysis, and gasification) conditions for biochar production or how these conditions affect the porosity of activated biochars.…”

Effects of Coproduct Uses on Environmental and Economic Sustainability of Hydrocarbon Biofuel from One- and Two-Step Pyrolysis of Poplar

“…Activated carbon is the highest value product analyzed in this study for biochar. Its selling price is between $1000 and $1500 per metric ton depending on the quality of the activated carbon 10 . The selling price used in this study was assumed to be $1100 per metric ton 7 .…”

“…With activated carbon the pores adsorb pollutants in either water or air waste streams. A study by researchers at Iowa State University found that converting biochar into activated carbon using steam is profitable 10 . Arena et al found that processing activated carbon from coconut shell instead of coal can greatly reduce the environmental burdens of activated carbon processing 11 .…”