Synergistic Chemical Looping Process Coupling Natural Gas Conversion and NO_x Purification

Abstract

We present a novel low-temperature chemical looping combustion scheme for simultaneous natural gas conversion into a sequestration-ready CO2 stream and NO x purification. The scheme employs nickel oxide (NiO) supported on ZrO2 as the oxygen carrier. In the process, CH4 reduces the oxidized carrier to Ni/ZrO2 in a co-current moving bed reactor, which is then oxidized back to NiO/ZrO2 by the NO x -laden flue gas in a fluidized bed reactor, completing the oxygen carrier loop. Thermodynamic studies demonstrate that the presence of CO2 does not significantly affect NO x purification performance at different flue gas flow rates. The operating temperatures of the reactors are selected based on NO x -temperature programmed oxidation (TPO) and CH4-temperature programmed reduction (TPR) experiments. Results show that the process can optimally operate at temperatures close to the combustion plants’ flue gas temperature of 400–500 °C, reducing the need for hot utilities. The study conducts comprehensive isothermal and autothermal analyses of the process to evaluate the effects of temperature and carrier flow rate on CH4 conversion, CO2 selectivity, carbon deposition, and NO x conversion. For the autothermal analysis, the CH4 reactor operates adiabatically, while the NO x reactor operates isothermally. Comparative studies with the conventional NO x selective catalytic reduction (SCR) process indicate an exergy efficiency and effective thermal efficiency (ETE) improvement of 9 and 18 percentage points, respectively. The findings suggest that this low-temperature chemical looping process is a promising solution for flue gas NO x treatment, utilizing cheaper natural gas as the reductant and eliminating environmental concerns, such as ammonia or urea slippage. Overall, this study contributes to the development of more efficient and sustainable methods for reducing NO x emissions.

Chemical looping methanol oxidation using supported vanadium phosphorous oxide carriers for formaldehyde production

“…To achieve stability of the oxygen carrier, its active components are often dispersed on a support. 42–46 Our preliminary analysis and literature indicate that SiO 2 can serve as a support for VOPO 4 as it does not react with either vanadium or phosphorous and has already been utilized as a carrier support for various applications. 31,47–50 The CLMO process using the VPO carrier can be broken down into two steps.…”

Carbon Dioxide Capture and Hydrogen Production with a Chemical Looping Concept: A Review on Oxygen Carrier and Reactor

“…In the oxidizer, the reduced OC is oxidized by air and exothermic heat (), while releasing oxygen-lean air. Through the above process, the direct reaction between fuel and air is avoided, and the CLC process can reduce the NO x emissions while realizing CO 2 capture. , Compared with combustion with CCS, CLC technology can eliminate the energy loss of separating CO 2 from effluent gas. At present, this technology has been applied to large-scale demonstration installations and has generated ∼100 kW th of the power generation. , ( 2 n + m ) Me italicx normalO italicy + normalC italicn normalH 2 italicm → ( 2 n + m ) normalM italicx normalO italicy − 1 + italicn normalCO 2 + italicm normalH 2 normalO Me italicx normalO italicy − 1 + 0.5 normalO 2 → Me italicx normalO italicy …”

Thermodynamic Evaluation of the Cross-Current Moving-Bed Chemical Looping Configuration for Efficient Conversion of Biomass to Syngas

“…Hence, without changing the reactor volume, the traditional BTS system can be easily transformed to a cross-current system to improve the syngas yield. Given the advantage of the novel cross-current system, a system-level performance assessment of the process is necessary, as showcased by previous works, − for determining the scale-up potential of the cross-current system compared to the conventional cocurrent system.…”