Proceedings of CUChE Alumni Symposium 2022
On “Circular Economy on Sustainable Basis: The Role of Chemical Engineers”
CUChEAA ISBN: 978-81-954649-1-3
December 2022 P a g e | 53 Volume 2, Issue 1
Production of syn-gas by the tri-reforming of methane over Ni/γ-Al
2
O
3
catalyst
Arisha Sharma and Prakash Biswas
*
Department of Chemical Engineering, Indian Institute of Technology Roorkee,
Roorkee-247667, Uttarakhand, India
*Corresponding author: Tel.: (+91)-1332-28-5820
Email: prakash.biswas@ch.iitr.ac.in; prakashbiswas@gmail.com
Abstract
Carbon dioxide and methane are emitted due to the combustion of fossil fuels which causes the greenhouse effect. Tri-
reforming utilizes these anthropogenic gases and converts them into synthesis gas. This study explored the tri-reforming of
methane over Ni/γ-Al
2
O
3
catalyst prepared by the
wet impregnation technique with different Ni metal loading (5-10 wt.%).
The physicochemical properties of the catalysts were characterized by X-ray diffraction, N
2
adsorption-desorption, and
temperature-programmed reduction techniques. The performance of these catalysts was evaluated in a packed bed reactor
at atmospheric pressure in the temperature range of 700-800 °C. The molar feed (CH
4
: CO
2
: H
2
O: O
2
: N
2
) composition of
(1: 0.5: 0.0125: 0.1: 1) was used for each experiment. Results demonstrated over 5% Ni/γ-Al
2
O
3
catalyst, constant CH
4
conversion of ~55% at both the temperatures (700 °C and 800 °C), and ~99% CO
2
conversion at 800 °C in TRM were
achieved. The optimum H
2
/CO molar ratio of ~(2.6- 2.7) was obtained at 800 °C over both 5% Ni/γ-Al
2
O
3
and 10% Ni/ γ-
Al
2
O
3
catalysts.
Keywords: Ni/ γ-Al
2
O
3
catalyst, tri-reforming of methane, CO
2
, synthesis gas, H
2
/CO ratio.
1. Introduction
The emission of greenhouse gases causing global
warming is a matter of concern. CH
4
and CO
2
are the
two most important anthropogenic greenhouse gases.
Recently proposed, dry-reforming of methane combines
CO
2
and CH
4
to generate syn-gas for clean liquid fuels
and valuable chemicals. However, this process is
endothermic in nature and requires high energy input,
and a significant problem is catalyst deactivation due to
carbon formation. A novel alternative, i.e., tri-reforming
of methane (TRM), has been proposed to overcome these
limitations. TRM is the combination of endothermic
methane steam reforming (Eq. 1), endothermic methane
dry reforming (Eq. 2), and exothermic partial methane
oxidation (Eq. 3)(Song and Pan 2004).
Methane steam reforming (MSR)
CH
4
+ H
2
O ↔ CO + 3H
2
, ΔH
⸰
298
= +206 kJ/mol (1)
Methane dry reforming (MDR)
CH
4
+ CO
2
↔ 2CO + 2H
2
, ΔH
⸰
298
= +247 kJ/mol (2)
Partial methane oxidation (PMO)
CH
4
+ 0.5O
2
↔ CO + 2H
2
, ΔH
⸰
298
= -35.6 kJ/mol (3)
TRM combines all these reactions (Eq. 1-3) to solve the
problems of being highly endothermic and catalyst
deactivation associated with MSR, MDR, and PMO. The
presence of O
2
and H
2
O in TRM is beneficial. PMO
being exothermic makes TRM mild endothermic as it
provides heat energy required for steam and dry
reforming and increases catalyst life by inhibiting coke
formation. In the MDR process, a few side reactions also
occur, such as reverse water-gas shift (RWGS) (Eq. 4),
boudouard (Eq. 5), methane cracking (Eq. 6), and CO
reduction (Eq. 7), etc.
CO
2
+ H
2
↔ CO + H
2
O, ΔH°
298
= 41 kJ/mole (4)
2CO ↔ CO
2
+ C
(s)
, ΔH°
298
= -172 kJ/mole (5)
CH
4
↔ 2H
2
+ C
(s)
, ΔH°
298
= 75 kJ/mole (6)
CO + H
2
↔
C + H
2
O, ΔH°
298
= -131 kJ/mole (7)
The significant advantages of the TRM process is that the
flue gas of the power plant can directly be used as a feed
without purification, and the control of the H
2
/CO molar
ratio in the syngas is also very flexible. However, the
significant challenges associated with the TRM process
include high operating temperature (500-800 °C), coke
formation, catalyst stability and deactivation, and syngas
with a constant H
2
/CO ratio for an extended period. As a
result, the development of a suitable catalyst and the mild
reaction condition process for producing syngas with the
appropriate H
2
/CO mole ratio is highly desirable.
Previous literature indicated that the noble metal-based
catalysts showed better methane and CO
2
conversion