High Temperature CaO/Y₂O₃ Carbon Dioxide Absorbent with Enhanced Stability for Sorption-Enhanced Reforming Applications

Abstract

To improve the stability of high temperature CO 2 absorbent for sorption enhanced reforming applications yttria supported CaO were synthesized using two methods: calcination of mixed salt precursors and wet impregnation of yttria support. According to XRD data, CaO does not interact with the yttria matrix. However, introduction of CaO drastically changes the morphology of primary yttria particles. Increase in CaO concentration results in gradual plugging of the smaller pores and sintering of yttria support. The CO 2 absorption uptake in recarbonation-decomposition cycles increases with increase in CaO content and reach 9.6 wt % at CaO content of 19.9 wt %. CaO recarbonation extent varies from 49 to 77%. CaO/Y 2 O 3 absorbents are extremely stable under overheating and maintain their capacity in long series of decomposition-recarbonation cycles even after calcination at 1350 °C. The novel material resists moisture and retains its strength during storage in the air. According to tests, CaO/Y 2 O 3 can be considered as a promising CO 2 absorbent for fixed bed sorption enhanced hydrocarbons reforming.

Dysprosium Oxide-Supported CaO for Thermochemical Energy Storage

“…In order to improve carbonation efficiency and hence cyclability, the use of synthetic CaO-based materials synthesized with sintering-resistant inert supports is well documented (for CO 2 capture applications) (Liu et al, 2012b). A variety of materials have been investigated, such as CaTiO 3 (Liu et al, 2012b), Al 2 O 3 (Broda et al, 2012), Y 2 O 3 (Derevschikov et al, 2011), SiO 2 (Li et al, 2014;Sanchez-Jimenez et al, 2014), and oxides of Si, Co, Ti, Cr, Ce, and Zr (Lu et al, 2009). Synthesis processes usually involve dispersing CaO in a stable, solid matrix made up of the inert material, acting to preserve the available active surface layer of CaO and preventing loss of conversion with cycling (Li et al, 2005).…”

Development of an effective bi-functional Ni–CaO catalyst-sorbent for the sorption-enhanced water gas shift reaction through structural optimization and the controlled deposition of a stabilizer by atomic layer deposition

“…Commonly used stabilizers can be classied into two different groups: (i) those forming a mixed oxide with CaO, such as Al 2 O 3 , SiO 2 , TiO 2 and ZrO 2 , [23][24][25][26] and (ii) inert stabilizers that do not react chemically with CaO under the relevant operating conditions, such as MgO, Y 2 O 3 , and ZnO. [27][28][29][30][31] Furthermore, to make calcium looping a viable option at the industrial scale (e.g., operation in circulating uidized beds) high CO 2 uptakes within relatively short residence times are required. The carbonation of CaO is known to proceed in two reaction regimes, 32,33 viz., the kinetically controlled carbonation followed by a sluggish diffusion-limited carbonation regime (the diffusivity of CO 2 in the CaCO 3 product layer, D CaCO 3 ¼ 0.003 cm 2 s À1 , is two orders of magnitude smaller than that in CaO, D CaO ¼ 0.3 cm 2 s À1 ).…”

Screening of inert solid supports for CaO-based sorbents for high temperature CO2 capture

“…Thus it is of great significance to develop high-reactivity CaO sorbents with stable capacity performance over multiple carbonation/calcination cycles. A variety of methods have been investigated to improve the performance of the CaObased sorbents, including (i) reactivating CaO-based sorbents by hydration [10,11]; (ii) producing CaO sorbents from sinteringresistant precursors [12,13]; (iii) modifying the structure of natural Ca-containing minerals by organic acids [8,14,15]; and (iv) introducing inert solid support as second-phase refractory 'spacer' to resist aggregations of CaCO 3 /CaO particles [16][17][18][19][20][21][22][23][24][25].…”

“…Recently, a novel inert support of Nd 2 O 3 was also reported, successfully improving both the CO 2 capture capacity and the durability of the sorbents [16]. Other supports, such as Y 2 O 3 [23,35], CeO 2 [32,34], Ca 2 MnO 4 [21], SiO 2 [22], CaTiO 3 [36,37], TiO 2 [37], and La 2 O 3 [21,38], have also been reported to be effective in promoting the CO 2 capture performance of the sorbents.…”