One-pot alkaline carbonization hydrothermal synthesis of halloysite nanotubes with amino groups over Pd@CeO2/halloysite to enhance catalysis of three-way reactions

The three-way catalytic activity of the halloysite (Hal)-supported Pd@CeO2 (P@C) catalyst was enhanced by hydrothermal carbonization. The P@C/4-1.0C-175H catalyst (P@C was loaded with carbonized Hal with a mass ratio of cellulose/Hal = 1, the temperature was 175 degrees C, and t = 4 h) showed higher catalytic efficiency than P@C/H (without modification) under optimal hydrothermal carbonization conditions, which was attributed to the large proportions of carbon and oxygen-containing functional groups on carbonized Hal. The T90 (full -con-version temperature) for CO conversion was decreased from 233 degrees C to 210 degrees C. On the other hand, the efficient one-pot alkaline carbonization hydrothermal synthesis combined hydrothermal carbonization and alkaline modification without complicated steps or additional active agents. The synthesis was modified, and the cellulose carbon source was substituted by lysine to induce a negative charge on the surface of Hal. The results indicated that P@C/4-1.0NC-175H exhibited strong metal-support interactions, abundant amino and oxygen-containing functional groups, and more oxygen vacancies and CeIII species. The T90 for CO conversion with P@C/ 4-1.0NC-175H was significantly decreased from 461 degrees C (P@C) to 174 degrees C. This research provides a simple method for enhancing metal-support interactions and improving catalytic performance.

Automated summary

The catalytic efficiency of Pd@CeO2 catalyst supported by Halloysite was enhanced by hydrothermal carbonization. The catalyst with carbonized Hal showed higher catalytic activity due to the proportion of carbon and oxygen functional groups. Furthermore, combining alkaline modification with hydrothermal carbonization significantly reduced the conversion temperature of CO.