Illinois State Geological Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, 615 E Peabody Drive, Champaign, Illinois 61820, USA.
Phys Chem Chem Phys. 2012 Dec 28;14(48):16633-43. doi: 10.1039/c2cp42209c. Epub 2012 Sep 18.
Reactive dynamics simulations with the reactive force field (ReaxFF) were performed in NVE ensembles to study the sintering of two solid calcium oxide (CaO) particles with and without CO(2) chemisorption. The simulated sintering conditions included starting adsorption temperatures at 1000 K and 1500 K and particle separation distances of 0.3 and 0.5 nm. The results revealed that the expansion of sorbent particles during CO(2) chemisorption was attributed to the sintering of two CaO-CaO particles. Increasing the adsorption temperature resulted in more particle expansion and sintering. The shorter the distance between two particles, the faster the rate of sintering during CO(2) adsorption. A detailed analysis on atom spatial variations revealed that the sorbent particles with a larger separation distance had a larger CO(2) uptake because of less sintering incurred. The chemisorptions of CO(2) on CaO particles sintered at high adsorption temperatures were also simulated to mimic the process of sorbent regeneration. It was found that regeneration would be more difficult for sintered particles than for fresh particles. In addition, a possible sintering barrier, magnesium oxide (MgO), was introduced to prevent CaO particles from sintering during CO(2) chemisorption. It was found that the MgO particles could reduce the sintering of CaO particles during CO(2) chemisorption. Simulation results from this study provided some guidelines on synthesizing or selecting sorbents with less sintering effect for multiple CO(2) adsorption-regeneration cycles.
采用反应力场（ReaxFF）进行非平衡态动力学模拟，研究了在有和没有 CO(2)化学吸附的情况下，两个固体氧化钙（CaO）颗粒的烧结过程。模拟的烧结条件包括起始吸附温度为 1000 K 和 1500 K 以及颗粒分离距离为 0.3 和 0.5 nm。结果表明，在 CO(2)化学吸附过程中，吸附剂颗粒的膨胀归因于两个 CaO-CaO 颗粒的烧结。吸附温度的升高导致更多的颗粒膨胀和烧结。两个颗粒之间的距离越短，在 CO(2)吸附过程中烧结的速度就越快。通过对原子空间变化的详细分析发现，由于烧结程度较小，分离距离较大的吸附剂颗粒具有更大的 CO(2)吸收量。还模拟了在高吸附温度下烧结的 CaO 颗粒上 CO(2)的化学吸附，以模拟吸附剂再生的过程。结果发现，与新鲜颗粒相比，烧结颗粒的再生会更困难。此外，引入了一种可能的烧结障碍物质氧化镁（MgO），以防止 CO(2)化学吸附过程中 CaO 颗粒的烧结。结果发现，MgO 颗粒可以减少 CO(2)化学吸附过程中 CaO 颗粒的烧结。本研究的模拟结果为在多次 CO(2)吸附-再生循环中合成或选择具有较小烧结效应的吸附剂提供了一些指导。
