Catalytic applications of large scale metal processing wastes

1. Catalytic applications of large scale metal processing wastes Justin Hargreaves

2. 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

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

4. Aluminium dross – aluminium production and recycling 5 x 106 t/year some dross recycled as deoxidiser in steel manufacture – rest in landfill Extracted metal content M. Balakrishnan et al., Green Chem. 13, 16 (2011).

5. 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)

6. Dross directly – impurities increase crystallite size Al extracted from dross Commercial Al source

7. Blast furnace slag240-290 x 106 t in 2008

8. Fly ash 430 x106 t in 2003

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

11. Coal fly ash – zeolite synthesis • One step (impure zeolite) – fly ash + 2M NaOH, 90°C, 96h • Two step – fly ash + 2M NaOH, 90°C, 6h, filtration, add aluminate solution to adjust Si/Al to 0.8-2, incubate at 90°C for 24h G. Hollman et al., Fuel 78, 1225 (1999).

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

13. Zeolite synthesis from slag • Materials 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

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

15. 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

17. http://www.redmud.org/

18. ICP analysis RM4 & RM7 same site but 24 month interval

19. XRD analysis of red mud samples

20. CH4 → C + 2H2 Landfill Associated petroleum gas Flaring and associated NOX

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

22. Maximum hydrogen formation rates at 800C: 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 800C(K Otsuka and co-workers, J Catal. 222, 520 (2004))

25. Post 800C reaction XRD analysis

26. RM 7 in-situ XRD, 72wt%C

27. Post 800C reaction TGA in 2%O2/Ar RM4 47.71 wt%C, RM6 43.49wt %C & RM7 38.06wt%C

28. Derivative TGA

32. Butane cracking

33. 72wt%C

35. RM 4 – 64wt% C

36. Acetonitrile – RM7

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

39. pH curves – raw RM7

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

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

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

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

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

45. Potential directions: generation of FeO42- c.f. waste hydrated ferrous sulfatefrom sulfate process for TiO2 production. N. Kanari et al. , JOM, 53,11,32 (2001)

46. 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

47. PZC – red mud

48. Carbonised RM7 – Cu2+ adsorption data 0.5g carbonised red mud column experiments