Conversion processes environmental impact

Phenol is an important raw material for the synthesis of petrochemicals, agrochemicals, and plastics. Examples of the uses of phenol as an intermediate include the production of bisphenol A, phenolic resins, caprolactam, alkyl phenols, aniline, and other useful chemicals. Today, almost 95% of worldwide phenol production is based on the so-called cumene process which is a three-step process (the conversion of benzene and propylene to cumene using supported phosphoric acid catalysts, the conversion of cumene to cumene hydroperoxide with air, and the decomposition of hydroperoxide to phenol and acetone with sulfuric acid). The great interest in the oxidation reaction of benzene to phenol is Unked to some disadvantages of the cumene process (environmental impact, production of an explosive hydroperoxide. 

Gage, S.J. and Chapman, R.A., "Environmental Impact of Solid Waste and Biomass Conversion-to-Energy Processes", in "Symposium Papers Clean Fuels from Biomass and Wastes", 465-482, Inst, of Gas Technology, Chicago (1977). 

Paskall (25) has recently reviewed the various modifications to the Claus process that result in optimum sulfur recovery efficiency. Overall plant conversion efficiencies in the range of 97% were considered to be the upper limit at the beginning of the 1970 s (26). While this is a very respectable conversion efficiency for an industrial process the unrecovered 3% in a 2,000 tonne/d sulfur plant represents 60 tonnes/d of sulfur lost, mainly to atmosphere as 120 tonnes/d of SO2. Modifications to the four stage Claus converter train however, can raise overall conversions to over 98.5% thus halving the sulfur loss to the plant tail gas. This either reduces environmental impact or the load on tail gas desulfurization units that will be discussed later. 

Helsen, L. and Van den Bulck, E. (2004) Review of thermochemical conversion processes as disposal technologies for chromated copper arsenate (CCA) treated wood waste, in Environmental Impacts of Preservative-Treated Wood, Florida Center for Environmental Solutions, Conference, Gainesville, Florida, February 8-11, Orlando, FL, pp. 277-94. 

The kinetic and thermodynamic characterisation of chemical reactions is a crucial task in the context of thermal process safety as well as process development, and involves considering objectives as diverse as profit and environmental impact. As most chemical and physical processes are accompanied by heat effects, calorimetry represents a unique technique to gather information about both aspects, thermodynamics and kinetics. As the heat-flow rate during a chemical reaction is proportional to the rate of conversion (expressed in mol s 1), calorimetry represents a differential kinetic analysis method [ 1 ]. For a simple reaction, this can be expressed in terms of the mathematical relationship in Equation 8.1 ... 

In the previous chapters, thermodynamic analysis is used to improve processes. However, as pointed out in Chapter 9 (Energy Conversion), the exergy analysis did not make any distinction between the combustion of coal and natural gas and, as a result, could not make any statements regarding toxicity or environmental impact of exploration, production and use of the two fuels. A technique that can do this is LCA. What exactly is life cycle analysis In ISO 14040 [1], life cycle analysis (or life cycle assessment) is defined as "the compilation and evaluation of the inputs, outputs and potential environmental impacts of a product throughout its life cycle."... 

We have our work divided into process engineering, process chemistry, catalysis, and support technology. As an example, one of the indirect liquefaction projects, tube wall reactor, deals with the design and operation of high thermal efficiency catalytic reactors for syn-gas conversion. Other activities are coal liquefaction properties of coal minerals, the role of catalysts, coal liquid product stability, and environmental impact—to name a few. 

Identifying the products (both intermediates and final products) from the SCWO process is an essential prerequisite for evaluating the environmental impact of the technology. Additionally, identification of products is key to optimizing the process parameters to obtain the desired conversion for the destruction of the pollutant. The intermediate products and their composition depend on the temperature, water density (or pressure), oxidant concentration, concentrations of other additives, if present, reactor surface, and the extent of the conversion. 

Most important are likely environmental factors associated with cultivation, crop management, and postharvest processes that can be controlled to some extent and on the other hand also have a large impact on the chemical composition, cell-wall architecture, or conversion processing behavior of plant biomass. These factors could form the basis of a testable strategy to decrease the variance associated with these characteristics. 

Bergman and Frisch [7] disclosed in 1966 that selective oxidation of n-butane was catalyzed by the VPO catalysts, and since 1974 n-butane has been increasingly used instead of benzene as the raw material for maleic anhydride production due to lower price, high availability in many regions and low environmental impact [8]. At present more than 70 % of maleic anhydride is produced from n-butane [6]. However, productivity from n-butane is lower than in the case of benzene due to lower selectivities to maleic anhydride at higher conversions and somewhat lower feed concentrations (< 2 mol. %) used to avoid flammability of a process stream. Under typical industrial conditions (2 mol. % n-butane in air, 673-723K, and space velocities of 1100-2600 h ) the selectivities [9] for fixed-bed production of maleic anhydride from n-butane are 67-75 mol. % at 70-85 % n-butane conversion [10]. Another unique feature of the VPO catalysts is that no support is used in partial oxidation of n-butane.Many studies of n-butane oxidation on the VPO catalysts indicated that crystalline vanadyl(IV) pyrophos-... 

As depicted in Figure 1, a life-cycle inventory may involve all stages in production, use, and disposal, including raw material extraction, transportation, primary processing, conversion to finished products, incorporahon into finished products, maintenance and repair, and disposal. The system boundary (indicated by the dashed line) dehnes those operahons to be included in the inventory of environmental impacts. 

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