Sol–Gel‐Derived, Calcium‐Based, Copper‐Functionalised CO₂ Sorbents for an Integrated Chemical Looping Combustion–Calcium Looping CO₂ Capture Process

Abstract

Using a sol–gel technique, new copper‐functionalised, calcium‐based CO2 sorbents were developed to integrate chemical looping combustion into the calcium looping scheme. In this process, the exothermic reduction of copper oxide with methane, carbon monoxide or hydrogen is used to provide the heat required to calcine (regenerate) calcium carbonate. The materials contained CuO and CaO in a molar ratio of either 1.3:1 or 3.3:1, were supported on Al2O3, MgO or MgAl2O4 and were characterised by means of X‐ray diffraction, N2 physisorption, scanning electron microscopy and temperature‐programmed reduction. All materials, independent of the precursors and support material used, possessed excellent cyclic oxygen‐carrying capacities. However, it was found that the presence of magnesium in the support stabilised the CO2 uptake and minimised carbon deposition. CuCa‐MgAl‐1.3:1 was the material that possessed the highest CO2 uptake of 0.13 g CO 2 gmaterial−1 after 15 cycles of repeated carbonation/calcination–redox reactions.

Investigating the Use of CaO/CuO Sorbents for in Situ CO2 Capture in a Biomass Gasifier

“…Kierzkowska and Muller synthesized CaO−CuO composite sorbents using a coprecipitation technique 16 and a sol−gel technique. 17 As in other studies, the authors highlighted the high sustained oxidation conversion (>98% over all cycles tested) for all tested cases although a gradual decay in carbonation performance was still observed under mild experimental conditions. While the combination of CaL and CLC for postcombustion applications has been shown to be promising, what has not been attempted so far is integrating the technology with precombustion technologies such as biomass steam gasification.…”

Ca-Cu Chemical Looping Process for Hydrogen and/or Power Production

“…In every case, the Cu phase reacted over 98%. Also these authors explored the effect that inert species might have on the chemical stability of the combined material, in this way they prepared via sol-gel materials supported on to Al O 3 , MgO and MgAl 2 O 4 with CuO and CaO molar ratio of 1.3:1 and 3.3:1 [43]. As found by other authors, the presence of Mg in the support stabilized the CO 2 uptake and minimized carbon deposition.…”

Clean Hydrogen Production Methods

“…Thus, so far, a large number of oxides have been considered. The water-splitting thermochemical cycle reactions can be mainly classified as (1) two-step water-splitting process [47][48][49][50][51] (2) iodine-sulfur process [52][53][54] and (3) calciumbromine process [55][56][57]. Table 2.3 summarizes the findings for various alkali metals used for watersplitting thermochemical cycles.…”

“…So far, several methods have been proposed to improve the CO 2 capture properties of limestone that include the thermal pretreatment or hydration [51][52][53]. Also, CaO is stabilized using high-Tammann-temperature support such as Al 2 O 3 , ZrO 2 , or MgO, to achieve a sinter-resistant material [54][55][56][57][58][59][60]. Recent finding suggests that hydrogen concentration in the product stream was higher for Ni/CaO compared to Ni/Al 2 O 3 .…”