POSSIBLE PATHWAYS FOR METHANE PRODUCTION FROM CO2 AND

HYDROGEN

A Presentation by:DEBAJYOTI BOSE

M Tech- REE, UPES

NECESSITY

Growing concerns about global climate change have increased attention on various approaches to reduce emissions of CO2 and other GHGs

Several relatively small-scale carbon capture and sequestration (CCS) approaches are currently in development and demonstration stages.

Technologies being developed today to capture and sequester CO2 require the isolation, compression, and transport of the CO2 to a sequestration site

THE BETTER ALTERNATIVE

Converting CO2 to a useful product involves reaction with H2

(hydrogen) over a metal catalyst to produce methane

This methanation process, also called the Sabatier reaction has been studied extensively

This same process is effective in converting carbon monoxide (CO) to methane

Methanation of both CO and CO2 are highly exothermic reactions

RESEARCH FINDINGS

Bugante et.al, 1989 conducted experiments on methane production from hydrogen with a gas mixture of CO and CO2

All chemicals used were of commercial grades

Measurement of CO2, CO, CH4 and H2 were done by the process of Gas chromatography

Nitrogen quantity is measured by Micro Kjeldahl method

Involved a two stage process

PROCESS BASICS

Thermophilic methanogens were used in a bioreactor

Preparation of methane sludge: Acclimatized at 55°C for at least 6 months to establish

methanogenic fermentation A portion of the sludge was inoculated in S medium as

described by Schauer et. Al, 1980

It is also incubated with gas mixture of 80% H2 and 20% CO2

“Gas recirculation at 55°C at pH 7.4”

SYSTEM COMPONENTS

Taken from Bugante et.al, 1989

SYSTEM ESSENTIALS Reactor volume = 500 ml 2 liter (each) rubber balloon at top Gas recirculation pump is used (Max

capacity 6L/minute)

A gas filter (2.5 cm dia) at bottom inside of column for gas recirculation

100 ml media used for cultivation of methanogens

Thermo-regulator and pH regulator

Baked clay, gravel balls and cristobalite PQ 10 no 1 and no 2 were tested for supporters

PROCESS PARAMETERS (REACTANTS)

Reactant Gas Mixture: N2 + CO2 + CO

Consumption rate of CO = 480 mmol/l-dCH4 production = 120 mmol/l-dGas recirculation speed = 18 l/hr

Second reactant is Hydrogen gas obtained from renewable electrolysis

Rate of Hydrogen Consumption = 1380 mmol/l-d

Conditions:

T = 55°CpH = 7.4

The S Medium

As additives the following were present:0.05% Trypticase0.05% yeast extraction

Cultivation was done for ten days with repeated supply of gas Gas mixture (80% H2 + 20% CO2)

Recirculation speed 18l/hr at 55°C

“pH at 7.4 maintained by adding 10% HCl or NaoH solution”

When turbidity of the medium reaches 0.5, medium was removed (OD660)

100 ml of S medium was newly supplied to the column for a methane production test

BASIC CHEMISTRY

50% N2 50% N2

25% CO → 2% CO 25% CO2 48% CH4

Reactant Product Gas Gas

+ H2

Calorific Valueof Product gas = 4621 Kcal/m³

STEPS INVOLVED

First step of the conversionHydrogen used = 2.24 l

Second step of conversionHydrogen used = 4.02 l

A Gas Balloon was used to achieve the second step of conversion of CO2

to CH4

Starting Gas at second step:17.9% N2

15.7% CO2

2.2% CH464.2% H2

Calorific Value = 2250 Kcal/m³

OTHER PROMISING PROCESSES

Sabatier Process Nickel was the first catalyst used (P. Sabatier, 1897) Further research (Ru, Rh, Co) To minimize cost and increase efficiency oxide (TiO2, MgO, Al2O3)

supports were used

“Ru-TiO2 being most stable & effective”

Sabatier Process with Bio-digester

Utilizing CO2 in biogas to effectively to produce bio methane This has the potential to replace expensive industrial operation

LIMITATIONS

The source of the reactants is a significant barrier to commercial use of Sabatier Process

Until the value of methane is greater than the value of hydrogen there is unlikely to be any market for CH4

created from hydrogen, regardless of the source of hydrogen

REFERENCES

Bugante, E. Shimomura, Y. Tanaka, T. Taniguchi, M Oi, S.: Methane production from hydrogen and carbon di oxide in a column bio reactor of thermophilic methanogen by gas recirculation. J. Ferment and Bioeng., 67, 419-421 (1989).

Schauer, N.L. and Ferry, J.: Metabolism of formate inMethanobacterium formicicum. J. Bacteriol,, 142, 800-807 (1980).

http://www.pennenergy.com/articles/pennenergy/2010/03/the-sabatier-reaction.html

THANK YOU !!!

A PRESENTATION BY

DEBAJYOTI BOSE

M TECH REE, UPES