Raw materials, substitution

Process Technology Evolution. Maleic anhydride was first commercially produced in the early 1930s by the vapor-phase oxidation of benzene [71-43-2]. The use of benzene as a feedstock for the production of maleic anhydride was dominant in the world market well into the 1980s. Several processes have been used for the production of maleic anhydride from benzene with the most common one from Scientific Design. Small amounts of maleic acid are produced as a by-product in production of phthaHc anhydride [85-44-9]. This can be converted to either maleic anhydride or fumaric acid. Benzene, although easily oxidized to maleic anhydride with high selectivity, is an inherently inefficient feedstock since two excess carbon atoms are present in the raw material. Various compounds have been evaluated as raw material substitutes for benzene in production of maleic anhydride. Fixed- and fluid-bed processes for production of maleic anhydride from the butenes present in mixed streams have been practiced commercially. None of these... 

In-Plant Waste Control. Pollution can be reduced or eliminated by process modification, chemical and raw materials substitution, or recovery of by-products. In addition, process modification generally increases product yield by incorporating control devices. 

Although carbon electrode production has been regarded as a mature business, the steady growth in demand and the need for improved electrodes has prompted ongoing development efforts in these areas (/) cost containment through raw material substitutions and process improvements (2) higher purity electrodes for those processes such as siUcon production (J) improvements in thermal shock resistance to enhance electrode performance and (4) better joining systems for prebakes. 

Economic evaluations of waste-reduction options should involve a comparison of operating costs to illustrate where cost savings would accrue. For example, a waste-reduction measure that reduces the amount of raw material lost down the drain during the process will reduce raw-material costs. Raw-material substitution or process changes may reduce the amount of solid waste that must be transported offsite, reducing the transport costs for waste disposal. 

Onsite Use and Reuse In-process and other onsite recycling options may be made more feasible by the adoption of other source reduction practices, such as waste segregation to cut down contamination of materials (e.g., solvents, baghouse dusts, lubricating oils, or rinse waters). Reuse as raw material substitute for another process. 

It may be noted that raw material substitution is easier in batch processes. Therefore, if one anticipates a varying range of feed stocks then batch processes may have some merit. In a similar note, if the same equipment is used to make a wide range of products (e.g., dyestuffs) then a batch process may be more suitable. 

It is very easy to show that whether it comes down to cost reduction, raw material substitution, raw material alternatives, or process engineering, well organized data become invaluable. Such data not only help to achieve goals quickly, at low cost, and successfully, but also help to build a process which organizes the present and future work and contributes to continuous progress. 

This new process illustrates two of the principles of green chemistry listed above. First of all, DMC is manufactured without using the hazardous phosgene feed. In fact, the phosgene is not even produced in the new pathway. Second, the DMC can be a raw material substitution for phosgene in the manufacture of pesticides and urethanes. Furthermore, the first principle of waste management hierarchy is demonstrated in that the by-product HCl is not produced (although, if market conditions were appropriate, the HCl produced could be purified and sold as a commodity). 

Agricultural residues are plentiful, widespread, and easily accessible, so fiber-board manufacturers are now studying their use as raw material substitutes [115, 116]. The strength properties in the MDFBs are mainly attributable to the physical and mechanical properties of individual wood fibers, fiber orientation, and the manner in which these components are combined in the structure. The chemical characteristics of peanut husks are found to be similar to those of other crop residues. The lower mechanical properties of MDFB panels with peanut husk could be due to the small size of peanut husk particles in the structure, which results in lower fiber aspect ratios, ultimately leading to poor fiber-to-fiber contact [116]. 

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