Ammonia Syngas Production from Coal Mine Drainage Gas with CO₂ Capture via Enrichment and Sorption-Enhanced Autothermal Reforming

Abstract

Current utilization practices have not fully appreciated the potential of coal mine drainage gas and have resulted in significant greenhouse gas emissions. This paper introduces a novel pathway of using coal mine drainage gas, regardless of its methane concentration, as a chemical feedstock for ammonia syngas production without CO2 emissions. The new pathway employs an enrichment process for concentrating drainage gas with low to medium CH4 concentrations and a sorption-enhanced autothermal reforming (SE-ATR) process for ammonia syngas production with in situ CO2 capture. Experimental results for the enrichment process showed that the CSIRO-developed single-stage adsorption process was able to concentrate drainage gas with 4.5 and 20.3% methane to 31.7 and 79.3%, respectively. Autothermal reforming (ATR) tests with a 30% CH4/air mixture using two commercial Ni-based catalysts demonstrated that, as the operating temperature decreased, the methane conversion rate decreased, while the CO2/CO molar ratio increased, leading to an almost constant H2 concentration (∼45–47% on a dry basis) in the product. With CaO as CO2 sorbents, the SE-ATR process further took the water–gas shift reaction to a complete extent at 600 °C through in situ CO2 capture and, thus, led to a completed methane conversion and a syngas product with a H2/N2 molar ratio of ∼3:2. When the CO2 sorbent became saturated, the SE-ATR test evolved to an ATR process. The experimental results for both ATR and SE-ATR tests were close to the thermodynamic equilibrium values. The H2/N2 ratio in the syngas can be further tuned to produce ammonia, which is a valuable commercial commodity with various favorable attributes and a H2 carrier for safer transportation and storage.

Recent Developments in Natural Gas Flaring Reduction and Reformation to Energy-Efficient Fuels: A Review

“…Further, the POX process can be started quickly, and its reaction is very fast. Recent research focused on finding alternative paths for conversion of natural gas (methane) to syngas through alternative routes by the combination of a dry reforming process with that of POX, called autothermal reforming (ATR), and it attracted the interest of many researchers. , The main advantages of the ATR process are the low energy requirement, fewer emissions, lower consumption of fuel, and tuning of the syngas ratio H 2 /CO by adjusting the inlet ratio of CH 4 /CO 2 /O 2 …”

“…149,247 The main advantages of the ATR process are the low energy requirement, fewer emissions, lower consumption of fuel, and tuning of the syngas ratio H 2 /CO by adjusting the inlet ratio of CH 4 /CO 2 /O 2 . 248 A catalyst with characteristics of high metal dispersion and resistance to coke deposition is an essential requirement for the reforming process, and various structured oxides such as hydrotalcites and perovskites were studied previously. 249 Structured oxides such as (ABO 3 ) and oxides of spinal type (AB 2 O 4 ) have well defined structures, which can provide high metal dispersion at extreme conditions of severe high temperature along with exposure to high oxidation−reduction processes.…”

Hydrogen Production from Coal Industry Methane

“…25). From the experimental results of the enrichment process [101] it is evident that a single-stage adsorption process involving carboncontaining sorbents can boost the concentration of the vent gas from 4.5 to 31.7%, and the concentration of methane, from 20.3 to 79.3% respectively. Autothermal reforming of a 30% CH 4 and air mixture over a nickel catalyst, yields gas mixture with H 2 concentration of about 45 to 47% (for dry gas).…”

Virtual Special Issue of 7th Sino-Australian Symposium on Advanced Coal and Biomass Utilisation Technologies

“…(10.1021/acs.energyfuels.9b02942) examine the effectiveness of venting on reducing CH 4 explosion pressure to enhance the safety of thermal processes for capturing and mitigating fugitive CH 4 . Yin et al (10.1021/acs.energyfuels.9b03076) present a new method for producing NH 3 syngas from coal mine drainage gas via enrichment and sorption-enhanced autothermal reforming. Wang et al (10.1021/acs.energyfuels.9b03083) synthesize a new Ir–Ni/SiO 2 catalyst via introducing NiO nanoparticles on the SiO 2 surface for enhanced performance on CO 2 reforming of CH 4 .…”