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Chemicals from Non-hydrocarbons
Published in James G. Speight, Handbook of Petrochemical Processes, 2019
The most important use of sulfur is for sulfuric acid production which is the most important and widely used inorganic chemical and is a widely used industrial chemical. Sulfuric acid is produced by the contact process where sulfur is burned in an air stream to sulfur dioxide, which is catalytically converted to sulfur trioxide. The catalyst of choice is solid vanadium pentoxide (V2O5). The reaction occurs at about 450°C (840°F), increasing the rate at the expense of a higher conversion. To increase the yield of sulfur trioxide, more than one conversion stage (normally three stages) is used with cooling between the stages to offset the exothermic reaction heat. Absorption of sulfur trioxide from the gas mixture exiting from the reactor favors the conversion of sulfur dioxide. The absorbers contain sulfuric acid of 98% concentration which dissolves sulfur trioxide. The unreacted sulfur dioxide and oxygen are recycled to the reactor. The absorption reaction is exothermic, and coolers are used to cool the acid: 2SO2+O2→SO3SO3+H2O→H2SO4
Life-cycle assessment-based comparison of different lignocellulosic ethanol production routes
Published in Biofuels, 2022
Govind Murali, Yogendra Shastri
The inventory for the biorefinery stage is based on the following assumptions: All types of low-lignin biomass give similar yield when they undergo the same treatments. Data related to process performance are taken from different sources for different feedstocks. Thus, operating conditions, scale of operation and so on may be different. However, these factors are ignored.The pre-treatment and hydrolysis of the polysaccharides result in the production of only glucose and xylose, and the production of other hexose or pentose monosaccharides is ignored. Oligomer formation has also been ignored.Recovery of 100% is assumed after the pre-processing of the biomass.The initial temperature of the biomass is assumed to be 30 °C.The operating conditions for hydrolysis and fermentation do not change based on the pre-treatment selection.Fermentation is assumed to take place at relatively low temperatures. Therefore, energy for fermentation has been neglected.The CO2 emitted during the fermentation stage is ignored for calculation of global warming potential since it is considered to be of biogenic origin.LSHS (low-sulfur heavy stock) has been used as fuel in boilers for steam generation.A contact process is assumed for sulfuric acid production, Solvay process for soda production and steam reforming for ammonia production.