Application of red mud as a basic catalyst for biodiesel production

Catalytic applications of waste derived materials

“…Liu et al applied red mud, dried at 200 C in air as a catalyst for soybean oil transesterication. 49 A 4 wt% loading of red mud resulted in >94% biodiesel yield aer 3 h at 65 C and a MeOH : oil molar ratio of 24, although the authors noted that their red mud sample contained much higher levels of Ca than commonly found in this waste stream, with the major component being CaCO 3 rather than iron oxides. Waste cement is composed of a similar mixture of metal oxides, principally calcium and iron oxides, with silica and alumina.…”

“…Other calcium-containing catalysts from waste include those from coral 44 bones, 8,45 scales 46 and calcite-containing rocks. [47][48][49][50][51][52] Corals are marine polyps which possess a calcareous exoskeleton formed from aragonite, a crystalline form of CaCO 3 . Roschat et al converted coral fragments to CaO by calcination at 700 C, and applied the resulting material as a catalyst for the transesterication of various oils, including palm, soybean, rice bran and waste cooking oils, with methanol.…”

“…64 The authors noted that red mud was less active than platinum group metal catalysts such as Ru/C or Pt/Al 2 O 3 , however this disadvantage is at least partially offset by the low cost of red mud, which adds value to this otherwise alkaline, problematic wastestream. 64,101 Due to the huge scale of red mud production, it offers great potential as a cost-effective and earth abundant catalyst/reagent, and has therefore also been employed for catalytic transesterication, 49 hydrodechlorination and hydrogenation as reviewed elsewhere. 102…”

Review of Heterogeneous Catalysts for Catalytically Upgrading Vegetable Oils into Hydrocarbon Biofuels

“…Red mud catalyst has high pore size and has been used for the transesterification of vegetable oils including soybean oil and Mahua oil. Red mud catalyst exhibits a high activity towards the transesterification of vegetable oils [108][109][110]. The properties of catalysts can be improved under proper conditions, but the commercialization of catalysts is still a challenge due to their large property difference.…”

Acetic Acid Ketonization over Fe3O4/SiO2 for Pyrolysis Bio‐Oil Upgrading

“…Generally, such waste is sent to landfill, and hence in conjunction with the scale (120 million tons per annum) of the production of this hazardous material, additional opportunities are sought to add value to Red Mud waste streams . Consequently, there are several reports of potential processes that address the valorisation of Red Mud, which include its use in construction, wastewater treatment, the preparation of geo‐polymers and magnetic materials, energy storage and catalysis for diverse transformations, such as bio‐diesel production, biomass pyrolysis, oxidation, hydrogen production and the upgrading of fast pyrolysis bio‐oils . Hematite, α‐Fe 2 O 3 , is a major catalytically active component of Red Mud, which constitutes typically 30–50 wt %, and has been investigated for the ketonisation of formic and acetic acid mixtures as model reactions for the upgrading of pyrolysis bio‐oils.…”