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The application of red mud as a pre-catalyst for the formation of functionalised carbons
Aims of the British Council red mud project:
-Investigate red mud for cracking of CH4 to produce H2 and C
CH4 → C + 2H2
-Apply the C so produced to water purification
-Valorisation - two “waste” products generating two useful products
Elemental composition of red mud samples (wt %)
Major elements Sample
code SiO2 Al2O3 Fe2O3 TiO2 CaO MgO Na2O K2O P2O5 MnO LOI
RM4 16.40 10.44 42.70 6.44 2.85 1.56 3.72 0.05 0.02 - 15.30
RM6 12.40 10.12 36.40 18.70 2.65 2.52 3.85 0.09 0.02 - 12.80
RM 7 14.60 23.51 36.79 0.74 1.18 0.07 6.08 0.02 0.15 0.12 16.47
RM4 & RM7 same site but 24 month interval
ICP analysis
RM4 15 m2g-1, RM6 8 m2g-1 & RM7 14 m2g-1
0
50
100
150
200
250
300
350
400
450
0 20 40 60 80 100 120 140 160 180 200Time on stream/min
10E7
Hyd
roge
n fo
rmat
ion
rate
/ mol
H2g
-1s-
1
RM4
RM6
RM7
Mass normalised hydrogen formation rates at 800°C
CH4:N2 =80:20, 60ml min-1, 0.4g
400 x 10-7 mol/g/s
0
50
100
150
200
250
300
350
0 10 20 30 40 50 60 70 80 90
2θ
Cou
nts
a,c,d,e
c,d
c,d, e
a,c,d,e
c
a,b,c
c,d,e ca a,c,d
c
RM4
RM7
RM6
a: Graphite (C) 23-0064 b: Iron (Fe) 03-1050c: Iron carbide (Fe3C) 03-0989d: Aluminium oxide (Al2O3) 26-0031e: Quartz (α-SiO2), 05-0490
d,e
ddd
e
ad
a,e
b,dccc,d
e
d
d
d
e
de e
ee
Post 800°C reaction XRD analysis
RM 7 in-situ XRD, 72wt%C
-40
-35
-30
-25
-20
-15
-10
-5
0
5
0 100 200 300 400 500 600 700 800Temperature/˚C
Wei
ght/%
RM4
RM6
RM7
Post 800°C reaction TGA in 2%O2/Ar
RM4 47.71 wt%C, RM6 43.49wt %C & RM7 38.06wt%C
SEM of post in-situ XRD RM 7 - 72wt%C
Butane cracking
Adsorption capacity of Cr, Cu and Pb on RM, ARM and CRM
pH Surface area
Cr
Cu
Pb
m2/g
mg/g
mmol/g
mg/g
mmol/g
mg/g
mmol/g
RM
11.5
10-15
1.3
0.025
8.9
0.14
133
0.64
ARM
4.5
45-48
1.7
0.033
3.5
0.055
9.0
0.045
CRM
8.2
70
0
0
25
0.39
94
0.45
CrO42-, Cu2+ & Pb2+
Methanol – CH3OH
Acetonitrile – CH3CN
700°C
800°C
900°C
C (wt%) H (wt%) N (wt%) 700°C 22.35 ± 4.77 - 1.31 ± 0.21800°C 61.40 ± 7.10 - 1.70 ± 0.25900°C 63.10 ± 0.52 - 1.60 ± 0.16
0 200 400 600 800 1000
40
50
60
70
80
90
100
Weig
ht (%
)
Temperature (oC)
700 oC 800 oC 900 oC
10 20 30 40 50 60 70 800
150
300
450
600
750
900
Inten
sity (
a.u.)
2θ
700 oC 800 oC 900 oC
500 1000 1500 2000 2500 3000
150
300
450
600
750
900
1050
1200
1350Int
ensit
y (a.u
.)
Wavenumber (cm-1)
700 oC 800 oC 900 oCD
G
Temp. (°C) C(wt%) H(wt&%) N(wt%)
Ni/ZSM-5 700 10.56 ± 0.12 0.46 ± 0.01 0.95 ± 0.02
Pd/ZSM-5 700 10.22 ± 0.01 0.43 ± 0.01 0.91 ± 0.01
RM7 700 17.50 ± 9.10 - -
Ni/ZSM-5 800 16.24 ± 0.74 - 1.41 ± 0.03
Pd/ZSM-5 800 16.00 ± 0.10 0.21 ± 0.04 1.25 ± 0.01
RM7 800 43.54 ± 7.53 - -
Ni/ZSM-5 900 44.82 ± 0.01 3.02 ± 0.06 -
Pd/ZSM-5 900 35.60 ± 0.10 - 2.16 ± 0.01
RM7 900 48.42 ± 0.71 - 0.57±0.21
C6H6/CH3CN
RM – C is very heterogeneous
Summary:
The efficacy of a variety of red muds for the production of hydrogen and graphitic carbons has been demonstrated.
Different carbon structures containing different degrees of functionality can prepared.
The presence of reduced iron phases in post reaction samples imparts magnetic behaviour which may facilitate envisaged downstream applications.
Acknowledgements:
Abdulrahman Alharthi, Vidya Batra, Malini Balakrishnan, Hannian Gu, Nidhi Gupta, Ian Pulford, Jose Rico Cerda, Snigdha Sushil.
Kim Wilson, Ross Blackley, Wuzong Zhou, David Morgan
British Council, India – UKIERI Grant SA07-19
Chinese Scholarship Council
Saudi Cultural Bureau