Catalytic applications of large scale metal processing wastes

Justin Hargreaves

Direct application as catalytic materials

Direct use as pre-catalysts

Modification to yield catalytically active phases

Use as precursors for the synthesis of active catalysts

Compositional variability

Paradox

M. Balakrishnan et al., Green Chem. 13, 16 (2011).

Waste materialReported production rateRed Mud120 million tonnes globally per annumAluminium dross5 million tonnes globally per annumFly ash430 million tonnes globally in 2003Slag from Fe manufacture 240-290 million tons globally in 2008Chicken egg shells4 million tonnes annually in China aloneRice husk ash~ 70 million tonnes globally per annum

Aluminium dross aluminium production and recycling 5 x 106 t/yearsome dross recycled as deoxidiser in steel manufacture rest in landfill

Extracted metal contentM. Balakrishnan et al., Green Chem. 13, 16 (2011).

Al89.1Mg3.8Si0.2Pb0.2Zn0.7Ca1.3Na0.7K0.8Fe2.5Mn0.6

Synthesis - structure directing agent, H3PO4 and Cr(III) acetate added

D= dross directly, E=extracted Al, P = pure Al(OH)3 (commercial)AW removes more weakly bound Cr.

J. Kim et al., J. Haz. Mater.169, 919 (2009)

Dross directly impurities increase crystallite sizeAl extracted from drossCommercial Al source

Blast furnace slag240-290 x 106 t in 2008

Fly ash 430 x106 t in 2003

The chemical composition of fly ash and blast furnace slag (wt%)M. Balakrishnan et al., Green Chem. 13, 16 (2011).

CaOSiO2Al2O3Fe2O3TiO2 MgOMnOP2O5K2OFly ash16.1237.0415.747.230.762.590.200.290.91Blast furnace slag40.0934.5814.781.530.785.290.27

Coal fly ash zeolite synthesis

One step (impure zeolite) fly ash + 2M NaOH, 90C, 96h

Two step fly ash + 2M NaOH, 90C, 6h, filtration, add aluminate solution to adjust Si/Al to 0.8-2, incubate at 90C for 24h

G. Hollman et al., Fuel 78, 1225 (1999).

C. Pradhan et al., J. Chem. Technol. Biotechnol. 81, 659 (2006)para-tertiarybutylphenol is the desired product, HZOP-31 is a fly ash derived zeolite X

Zeolite synthesis from slagMaterials containing in excess of 15wt% CaO unsuitable for zeolite synthesis formation of calcium silicate inhibits zeolite nucleation

Two stage method react with H3PO4 and then NaOH hydroxyapatite/zeolite X composite

New method treat with HCl and then further treat leached solution and residual SiO2

Y Kuwahara et al., J. Mater. Chem. 20, 5052 (2010).

Red Mud waste product of the Bayer Process for Al manufacture

Bauxite residue after treatment with caustic soda, extraction of liquid and drying

Al2O3.xH2O + 2NaOH 2NaAlO2 + (x+1) H2O

Variable composition, iron is a major phase,120M tonnes produced per annum

http://www.redmud.org/

RM4 & RM7 same site but 24 month intervalICP analysis

XRD analysis of red mud samples

CH4 C + 2H2LandfillAssociated petroleum gasFlaring and associated NOX

Mass normalised hydrogen formation rates at 800C CH4:N2 =80:20, 60ml min-1, 0.4g

Maximum hydrogen formation rates at 800C:

RM4 (15m2g-1) - 380 x 10-7 mol H2 g-1 s-1

RM7 (14m2g-1) 170 x 10-7 mol H2 g-1 s-1

RM6 (8m2g-1) 50 x 10-7 mol H2 g-1 s-1

cf 4.58 x 10-4 mol H2 g-1 s-1 reported for 38 wt% Fe2O3/Al2O3 at 800C (K Otsuka and co-workers, J Catal. 222, 520 (2004))

Post 800C reaction XRD analysis

RM 7 in-situ XRD, 72wt%C

Post 800C reaction TGA in 2%O2/ArRM4 47.71 wt%C, RM6 43.49wt %C & RM7 38.06wt%C

Derivative TGA

Butane cracking

72wt%C

RM 4 64wt% C

Acetonitrile RM7

Ferromagnetism imparted by the presence of iron and iron carbide(s)

pH curves raw RM7

Uptake of Pb () and Cu () by carbonised red mud.

Langmuir adsorption capacity of Cr, Cu and Pb on RM, ARM and CRM I. Pulford et al., J. Env. Manage. 100, 59 (2012)

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

R. Lago et al., Fuel 124, 7 (2014)

E. Karimi et al., Appl Catal B: Env 145, 187 (2014)

J. Kastner et al RSC Adv 5 29375 (2015)

Potential directions:

generation of FeO42-

c.f. waste hydrated ferrous sulfate from sulfate process for TiO2 production.

N. Kanari et al. , JOM, 53,11,32 (2001)

Acknowledgements:Ian Pulford, Vidya Batra, Malini Balakrishnan Hugh Flowers Jim Kastner and Jose Rico

Snigdha Sushil, Nidhi Gupta, James Wigzell, Jilliann Clapp, Abdullah Alabdulrahman, Abdulrahman Al Harthi, Kim Wilson , Ross Blackley, Wuzong Zhou

British Council, India UKIERI Grant SA07-19

PZC red mud

Carbonised RM7 Cu2+ adsorption data0.5g carbonised red mud column experiments