Upgrading Biochar into Activated Carbon Materials through Physical Activation

June 14th, 20132013 Midwest Biochar Conference

Champaign, Illinois

Joseph Polin*, Zhengrong Gu, Xiaomin Wang

Ag. & Biosystems Engineering Dept. South Dakota State University

Brookings, South Dakota

Outline

• Introduction• Materials and Methods• Experiments• Results• Conclusion

Introduction

• High demand for alternative energy• Reduce greenhouse gases• Clean renewable biofuels– Future 2nd generation technologies– Inedible lignocellulosic biomass

feedstocks– Thermochemical conversion

Thermochemical Conversion

• Fast pyrolysis– Thermal decomposition (typically 500-600°C) of biomass

in the absence of oxygen

• Variety of biomass feedstocks

• Yields 50-70 wt. % bio-oil– Liquid precursor to drop-in biofuels compatible with

current petroleum infrastructure

• Byproducts– Bio-char and synthesis gas (syngas)

Bio-char

• Yield 10-30 wt. %

• Composition– Carbon & Ash (minerals)

• Proposed uses– Soil amendment– Carbon sequestration

method– Burned for additional

process heat

Syngas

• Yield 15-20 wt. %

• Composition– CO2, CO, H2, CH4

• Proposed uses– Fischer-Tropsch

synthesis– Burned for additional

process heat

Typical Fast Pyrolysis Process

FastPyrolysisReactor

CondenserSystem

CombustionSystem

Biomass

Bio-Char

Bio-Oil

Syngas

Process Heat

Project Scope

• Activation methods– Physical or chemical activation– Oxidative reactants interact with

carbon matrix to develop porosity and increase surface area

• Flue gas components CO2 & H2O• Fast Pyrolysis Syngas

• Upgrade bio-char into activated carbon– Another value added co-product will help improve

overall economic potential of thermochemical platform

Activated Carbon

• Potable water treatment– Increasing global population in

developing countries increases demand for clean water

• Air purification and mercury control– New EPA emissions regulations for

coal-fired power plants and large boilers/incinerators

• Global market expects a compound annual growth rate of 11.1% from 2011 to 2016*

*MarketsandMarkets.com – Market Report: Activated Carbon

Equipment

• Fixed Bed Reactor– Load bio-char in mesh basket– Adjustable gas flow

• Micromeritics TriStar 3000– N2 adsorption isotherm– Measure BET surface area

CO2 Experiments

• Boudouard reaction CO2 (g) + C (s) 2 CO (g)

Results – CO2 @ 0.7 L/min

Results – CO2 @ 0.7 L/min

Results – CO2 Flow Rate Analysis

• Comparison of Trend Line Peaks

Steam Experiments

• Multiple Reactions Occur Simultaneously

• H2O (g) + C (s) CO (g) + H2 (g)

• 2 H2 (g) + C (s) CH4 (g)

• H2O (g) + CO (g) H2 (g) + CO2 (g)

• CO2 (g) + C (s) 2 CO (g)

Activation (carbon conversion %)

Results – H2O @ 1 mL/min

Results – H2O @ 1 mL/min

Results – H2O Flow Rate Analysis

• Comparison of Trend Line Peaks

CO2/H2O Mixture• Comparison of Trend Line Peaks @ 900C

Syngas Experiments

Carbon Dioxide 41.99%

Carbon Monoxide 50.82%

Methane 0.27%

Ethane 1.10%

Hydrogen 4.55%

Propane 1.18%

Ammonia 0.09%

• Typical syngas products from fast pyrolysis system*

• CO2 and CO account for almost 93%

• Same Boudouard reaction for activation

*NREL 2010 Technical Report: Techno-Economic Analysis of Biomass Fast Pyrolysis to Transportation Fuels

Syngas Activation

Syngas Activation

Results – Flow Rate Analysis• Comparison of Trend Line Peaks @ 900C

Syngas EffectivenessLangmuir Kinetic Mechanism

1. CO2 initial adsorption with C

2. CO blockage of C active site

3. CO desorption and development of porosity

Proposed Integration

FastPyrolysisReactor

CondenserSystem

CombustionSystem

BiocharActivation

Reactor

Biomass

Bio-Char

Bio-OilSyngas

Activated Carbon

Improved Syngas with higher CO conc.

Process Heat

Conclusion• Physical activation effectively increased surface area

of starting bio-char

• Lower flow rates and higher temperature (900C) create higher surface area

• Fast Pyrolysis Syngas develops best activated carbon on Surface Area x Yield % basis

• Produce maximum amount of activated carbon at 40% conversion

Future Work

• New reactor using rotary furnace

• Different types of bio-char

• Detailed economic analysis for bio-oil production

Acknowledgements

• Funding Agency

• Prof. Zhengrong Gu’s Research Team– Hong Jin– Xiaomin Wang– Sihan Li

Thank YouAny Questions?