Hydrogen Production from the Steam−Iron Process with Direct Reduction of Iron Oxide by Chemical Looping Combustion of Coal Char

Abstract

Experimental results performed with a fluidized-bed reactor supported the feasibility of the three processes including direct reduction of iron oxide by char, H2 production by the steam−iron process, and the oxidation of Fe3O4 resulting from the steam−iron process to the original Fe2O3 by air. Chars resulting from a Chinese lignite loaded with K2CO3 were used successfully as a reducing material, leading to the reduction of Fe2O3 to FeO and Fe for the steam−iron process, which was confirmed by both the off-gases concentrations and X-ray diffractometer analysis. The reduction of Fe2O3 by K-10-char at 1073 K is desirable from the perspective of the carbon conversion rate and high concentration of CO2. The carbon in char was completely converted to CO2 when the mass ratio of Fe2O3/K-10-char was increased to 10/0.3. The oxidation rate of K-10-char by Fe2O3 without a gasifying agent was comparable to the K-10-char steam gasification rate. The fractions of FeO and Fe in the reduced residue were 43 and 57%, respectively, in the case of 3 g of Fe2O3 and 0.5 g of K-10-char, which was verified by the total H2 yield equaling 1000 mL/g K-10-char from the steam−iron process. The time that it took to achieve complete oxidation of Fe3O4 to Fe2O3 by air with an 8.7% O2 concentration at 1073 K was about 15 min.

Thermodynamic analysis of chemical-looping hydrogen generation

“…Solid fuels such as coal char can be used as reducing materials in CLC. Yang et al [26] investigated H 2 production in a steam-iron process via FeO reduction using the CLC of coal char. FeO was used to oxidize coal char into CO 2 production via the steam-iron process.…”

Advancements in Development of Chemical-Looping Combustion: A Review

“…Solid fuels, such as coal char, were reported being used as reducing materials in CLR. Yang et al [97] investigated H 2 production from steam-iron process with reduction of iron oxide by CLC of coal char. Iron oxide was used to oxidize the coal char into CO 2 reduction of char were feasible for H 2 production through the steamiron process.…”

Chemical and calcium looping reforming for hydrogen production and carbon dioxide capture

“…This scheme was also explored experimentally using a lignitic coal and its chars (Yang, Cai, & Li, 2008) and a small fluidized-bed reactor using batches of haematite or Fe 2 O 3 . It demonstrated successful reduction of the haematite with potassium carbonate-promoted chars; production of H 2 via the reaction of water with the FeO; Fe produced by reaction with char; and final oxidation of the resulting magnetite (Fe 3 O 4 ) to haematite (Fe 2 O 3 ) by reaction with air.…”