Carbon/iron co-product from clean hydrogen production as the multifunctional catalyst for efficient wastewater remediation

Abstract

Hydrogen (H2) is not only an important chemical raw material but also an extremely important green energy. CH4 cracking plays an essential role in the H2 production process. In the absence of a catalyst, the cracking temperature needs to reach 1200 ℃. A suitable catalyst can reduce the cracking temperature to 900℃, significantly reducing energy consumption. In Chapter 4, when iron (Fe) ore is used as a catalyst, high and efficient CH4 cracking is achieved. A large amount of solid waste is generated in this process, and 3 tons of solid waste is generated for every 1 ton of H2 produced. I demonstrated that this Fe-containing solid waste (Fe@C) is an efficient Fenton reaction catalyst.

In the Fenton reaction, a large amount of hydrogen peroxide (H2O2) is used. There are certain risks in the storage and transportation of H2O2. If the in-situ generation and application of H2O2 can be achieved, the application of the Fenton reaction in organic wastewater treatment will be accelerated. In Chapter 5, I found that Fe@CNO-O is an efficient catalyst for the preparation of H2O2 by O2 reduction reaction (ORR). I showed that Fe@CNO is a tri-functional material as an adsorbent, a Fenton process catalyst, and an ORR catalyst for H2O2 production. These functions Ire combined to demonstrate a new water treatment process.

ORR for H2O2 production is generally coupled with oxygen evolution reaction (OER), which has a high energy consumption. In Chapter 6, I innovatively coupled ORR and chlorine evolution reaction (CER), which reduced energy consumption and in-situ generated H2O2 and CI2, which improved the overall economic efficiency. The H2O2 electrode structure was optimized for the industrial current density level of 300mA/cm2. When Fe@C was loaded in a fixed bed reaction, the in-situ generated H2O2 flowing through the reactor continuously degraded high concentrations of Rh-B for more than 120 h.