Upgrading Biochar into Activated Carbon Materials through Physical Activation

June 14th, 2013 2013 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

Fast Pyrolysis Reactor

Condenser System

Combustion System

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 Effectiveness Langmuir Kinetic Mechanism 1. CO2 initial adsorption with C

2. CO blockage of C active site

3. CO desorption and development of porosity

Proposed Integration

Fast Pyrolysis Reactor

Condenser System

Combustion System

Biochar Activation

Reactor

Biomass

Bio-Char

Bio-Oil Syngas

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 You Any Questions?