Abstract
Environmental considerations will probably change automobile fuels from gasoline and gas-oil to hydrogen (as fuel cell) in the future. Problems of fossil fuels include producing gaseous pollutants, such as NOx, CO, and even SO2 (from incomplete-hydrotreated fuels), which need catalytic converters and greenhouse gas emission (such as CO2, CH4, N2O) from the exhaust with a drastic effect on global warming1. Hydrogen usage in fuel cells generates only harmless water vapor2. Another future promising application of hydrogen fuel cells may be in small power plants without pollutants or greenhouse gas emission. Nowadays, power plants of industrial countries are coal-based with high SO2, NOx, CO2, mercury, and fly-ash emissions. Flue gas desulfurization of such power plants with CaO (dry method) or Ca(OH)2 (wet method) is a costly process3. In addition, SO2 reaction with lime shows pore mouth closure and incomplete conversion problems due to high molar volume ratio of CaSO4 to CaO4. The environmental preference of natural gas in terms of producing hydrogen over coal is a very interesting issue. Natural gas sweetening is very simple, whereas coal desulfurization is almost impossible. Moreover, the amount of greenhouse gas (CO2) emissions from natural gas-based combustion is about 45 % of coal-based power plants5,6. Industrial hydrogen production plants are usually based on catalytic steam reforming (SR) of natural gas to synthesis gas (CO+3H2), water-gas shift reaction for converting CO into CO2, CO2 absorption, and methanation of trace-remaining carbon oxides7. Conventional steam reforming is a highly endothermic reaction and needs a big top-fired or side-fired furnace for external heating of Ni-packed tubes8. Steam reforming by methane as the feed stock has been extensively studied in the literature9–12. Another method for producing hydrogen or synthesizing gas from natural gas is partial oxidation method. This method includes a highly exothermic reaction with hot spot, sintering of active catalyst sites, and even run-away problems13–15. An interesting alternative for steam reforming is the autothermal reforming method with internal heat generation by oxygen or air injection to the steam reforming system and elimination of its costly furnace16,17. ATR (autothermal reforming) combines thermal effects of partial oxidation and steam reforming reactions by feeding natural gas, water vapor, and air (or oxygen) into the reactor. Steam reforming and oxidation of methane occur simultaSimulating and Optimizing Hydrogen Production by Low-pressure Autothermal Reforming of Natural Gas using Non-dominated Sorting Genetic Algorithm-II
Highlights
Environmental considerations will probably change automobile fuels from gasoline and gas-oil to hydrogen in the future
As the reactor simulations concern the autothermal reforming of methane to synthesis gas on supported Ni catalysts, the rate equations for total combustion, steam reforming, and water–gas shift reactions have to be combined in the calculations
In the case of fuel-cell application, the fixed-bed catalytic autothermal reactor operated at atmospheric pressure
Summary
Environmental considerations will probably change automobile fuels from gasoline and gas-oil to hydrogen (as fuel cell) in the future. Industrial hydrogen production plants are usually based on catalytic steam reforming (SR) of natural gas to synthesis gas (CO+3H2), water-gas shift reaction for converting CO into CO2, CO2 absorption, and methanation of trace-remaining carbon oxides[7]. Steam reforming by methane as the feed stock has been extensively studied in the literature[9,10,11,12] Another method for producing hydrogen or synthesizing gas from natural gas is partial oxidation method. ATR (autothermal reforming) combines thermal effects of partial oxidation and steam reforming reactions by feeding natural gas, water vapor, and air (or oxygen) into the reactor. In Mohanty’s25 study, real parameter non-dominated sorting genetic algorithm was used to obtain a Pareto optimal set of process parameters for producing synthesis gas from combined carbon dioxide reforming and partial oxidation of natural gas over a Pt/Al2O3 catalyst. The optimization parameters were H2O/CH4 and O2/CH4 in the feed, as well as feed stream flux and temperature
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call