Advances in Nitrogen Carriers for Chemical Looping Processes for Sustainable and Carbon-Free Ammonia Synthesis

Abstract

The use of ammonia as a hydrogen carrier has generated considerable interest in developing more renewable and long-lasting methods for ammonia production. Collaborative efforts among research institutes, industries, and governments are underway to produce carbonfree ammonia and achieve net-zero emissions by 2050. One largely emerging approach, namely, chemical looping ammonia production (CLAP) with high product selectivity and energy efficiency that utilizes nitrogen carrier materials under atmospheric pressure may greatly reduce this process. Despite recent advancements, several key challenges related to the thermodynamics, kinetics, mechanisms, and environmental impacts of CLAP remain unresolved. This review provides a comprehensive overview of the progression and breakthroughs in this captivating domain, contrasts the properties of nitrogen carriers deployed in assorted CLAP processes alongside thermodynamic and kinetic considerations, and offers insights into the future trajectory of CLAP.

Towards green and efficient chemical looping ammonia synthesis: design principles and advanced redox catalysts

“…Although there have been some excellent reviews and books covering chemical looping ammonia synthesis, 27,[33][34][35][36][37][38][39][40][41][42][43][44][45][46] they tend to focus on the materials development of nitrogen or hydrogen carriers in CLAS. In this review, to propose and discuss strategies and advances for lowering reaction temperatures and increasing ammonia productivity towards green CLAS.…”

Palladium‐Silver Alloys Deposited on Different Carriers for Dehydrogenation of Formic Acid

“…The catalytic performance of PdÀ Ag alloys on the dehydrogenation of formic acids can be enhanced by introducing silver, which is consistent with the literature. [52] The Pd 1 Ag 1/2 /mpg-C 3 N 4 showed the best catalytic activity for the dehydrogenation of formic acid, which could be prepared in 45 min at room temperature (303 K) to obtain about 1.5 mmol of hydrogen. The corresponding TOF values of Pd/mpg-C 3 N 4 , Pd 1 Ag 1/8 /mpg-C 3 N 4 , Pd 1 Ag 1/4 /mpg-C 3 N 4 and Pd 1 Ag 1/2 /mpg-C 3 N 4 were 102, 170, 219, and 264 h À 1 , respectively (Figure 5b).…”

“…Consequently, C 3 N 4 is a good candidate for heterogenous catalytst for application in green and sustainable catalytic processes. [52] Herein, a heterogeneous catalyst for dehydrogenation of the FA was prepared by depositing PdÀ Ag particles on mesoporous carbon nitride (mpg-C 3 N 4 ) and other substrates. The structure and the performance of the catalyst were well investigated (Scheme 1).…”

Manganese-based A-site high-entropy perovskite oxide for solar thermochemical hydrogen production

“…1–5 To realize large-scale hydrogen production and store intermittent solar energy, solar-driven thermochemical hydrogen (STCH) attracts considerable attention because it utilizes the full spectrum of solar energy through a two-step redox cycle. 6–10 (1) The first step of the process involves the reduction of metal oxide under high temperatures ( e.g. , T > 1473 K) and low P O 2 (partial pressure of oxygen), resulting in the production of oxygen vacancies.…”