SDG-Based HAZOP and Fault Diagnosis Analysis to the Inversion of Synthetic Ammonia

This paper presents some practical applications of signed directed graphs （SDGs） to computeraided hazard and operability study （HAZOP） and fault diagnosis, based on an analysis of the SDG theory. The SDG is modeled for the inversion of synthetic ammonia, which is highly dangerous in process industry, and HAZOP and fault diagnosis based on the SDG model are presented. A new reasoning method, whereby inverse inference is combined with forward inference, is presented to implement SDG fault diagnosis based on a breadth-first algorithm with consistency rules. Compared with conventional inference engines, this new method can better avoid qualitative spuriousness and combination explosion, and can deal with unobservable nodes in SDGs more effectively. Experimental results show the validity and advantages of the new SDG method.

Recovery of Hydrogen from Ammonia Plant Tail Gas by Absorption-Hydration Hybrid Method

In this work, the absorption-hydration hybrid method was used to recover （hydrogen ＋ nitrogen） from （hydrogen ＋ nitrogen ＋ methane ＋ argon） tail gas mixtures of synthetic ammonia plant through hydrate formation/dissociation. A high-pressure reactor with magnetic stirrer was used to study the separation efficiency. The in-fluences of the concentration of anti-agglomerant, temperature, pressure, initial gas-liquid volume ratio, and oil-water volume ratio on the separation efficiency were systematically investigated in the presence of tetrahydro-furan （THF）. Anti-agglomerant was used to disperse hydrate particles into the condensate phase for water-in-oil emulsion system. Since nitrogen is the material for ammonia production, the objective production in our separation process is （hydrogen ＋ nitrogen）. Our experimental results show that by adopting appropriate operating conditions, high concentration of （hydrogen ＋ nitrogen） can be obtained using the proposed technology based on forming hydrate.

Ultrafine nano-copper derived from dopamine polymerization&synchronous adsorption achieve electrochemical purification of nitrate to ammonia in complex water environments

Electrochemical-nitrate-reduction-reaction(eNitRR)synthesis of ammonia is an effective way to treat ni-trate wastewater and alleviate the pressure of the Haber-Bosch ammonia production industry.How to develop effective catalysts to electrochemically reduce nitrate to ammonia and purify sewage under com-plex environmental conditions is the focus of current research.Herein,the dopamine polymerization pro-cess and the[(C_(12)H_(8)N_(2))_(2)Cu]^(2+)complex embedding process were run simultaneously in time and space,and ultrafine Cu nanoparticles(Cu/CN)were effectively loaded on nitrogen-doped carbon after heat treat-ment.Using Cu/CN as the catalyst,the ammonia yield rate and Faradaic efficiency of the electrochemical conversion of NO_(3)^(-)to NH_(3)are highly 8984.0μg h^(−1)mg cat.^(−1)and 95.6%,respectively.Even in the face of complex water environments,such as neutral media,acidic media,coexisting ions,and actual nitrate wastewater,nitrate wastewater can be effectively purified to form high value-added ammonia.The strat-egy of simultaneous embedding increases the exposure rate of Cu sites,and the support of CN is also beneficial to reduce the energy barrier of ^(∗)NO_(3)activation.This study rationally designed catalysts that are beneficial to eNitRR,and considered the situation faced by practical applications during the research stage,reducing the performance gap between laboratory exploration and industrial applications.

NO hydrogenation to NH3 over FeCu/TiO_(2) catalyst with improved activity

Ammonia is crucial in industry and agriculture, but its production is hindered by environmental concerns and energy-intensive processes. Hence, developing an efficient and environmentally friendly catalyst is imperative. In this study, we employed a straightforward and efficient impregnation technique to create various Cu-doped catalysts. Notably, the optimized 10Fe-8Cu/TiO_(2) catalyst exhibited exceptional catalytic performance in converting NO to NH3, achieving an NO conversion rate exceeding 80% and an NH3 selectivity exceeding 98% at atmospheric pressure and 350 °C. We employed in situ diffuse reflectance Fourier transform infrared spectroscopy and conducted density functional theory calculations to investigate the intermediates and subsequent adsorption. Our findings unequivocally demonstrate that Cu doping enhances the rate-limiting hydrogenation step and lowers the energy barrier for NH3 desorption, thereby resulting in improved NO conversion and enhanced selectivity toward ammonia. This study presents a pioneering approach toward energy-efficient ammonia synthesis and recycling of nitrogen sources.