Abstract

In this study, several process alternatives for the permanent sequestration of carbon dioxide (CO2) as solid carbonates are evaluated. Although the formation of mineral carbonates is thermodynamically favourable, it does not occur significantly due to kinetic limitations and the formation of products that hinder the evolution of the process. Several biological organisms, including corals, have developed different mechanisms for accelerating the process and managing undesirable products. In this report, we propose biomimicking approaches to precipitate solid carbonates while limiting the amount of energy required or using the produced by-products to generate valuable materials.

A few processes alternatives are described and evaluated in this study. In all these explored cases CO2 mineralization requires divalent cations such as Ca++ or Mg++. These could be sourced from sea water or land based silicates containing these cations. Sea-water based source results in two attractive options, namely: 1. electrochemically assisted precipitation of carbonates with production of sales of Cl2 or HCl; 2. electrochemically assisted precipitation of carbonates and production of Vinyl Chloride Monomer (VCM) and polymerization into Polyvinyl Chloride (PVC), with sales of PVC; the land based source results in further in options 3, and 4: 3. electrochemically assisted precipitation of carbonates with in-situ mining of silicates; and 4. ammonia assisted precipitation of carbonates with in-situ mining of silicates. This study explores the technical feasibility of these options further.

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