General chemical feedstock

Waste plastic is changed by heat or chemical agents into chemicals that might be used in the production of new polymers or as general chemical feedstocks (Al-Salem et al., 2010). Monomer recovery works well with source-separated plastics whereas general feedstock recovery is better suited for mixed plastic waste. 

About half of all zinc oxide produced is used by the rubber industry. About 10% of the zinc oxide is used by the coatings industry. Another 10% is used in the photocopying process. ZnO is also used in ceramics and as a general chemical feedstock. 

New product introductions are generally heavily supported by the technical service function. Many customers using chemical feedstocks to produce multicomponent products for the consumer market require extensive on-line evaluations of new raw materials prior to their acceptance for use. An example of this would be the use of a new engineering polymer for the fabrication of exterior automobile stmctural panels. Full-scale fabrication of the part foUowed by a detailed study of parameters, such as impact strength, colorant behavior, paint receptivity, exterior photodurabiHty, mar resistance, and others, would be required prior to making a raw materials change of this nature. 

TSCA poses a new challenge to universities. While toxics are uniquely a chemical problem, their impacts extend to involve other disciplines as well. The life cycle of a toxic substance starts with chemical feedstocks. It continues through the myriad steps of manufacture and processing, through use, and ends only after end-product disposal. During this cycle there are many chances for "leaks" into the environment. Risks posed may appear primarily as risks to occupational safety and health, to general human health, or to particularly sensitive or important... 

Acetylene is a tricky chemical feedstock. It is extremely reactive (and explosive) and impractical to transport. Generally, the industrial processes that use acetylene are close to the acetylene-generating source. Despite all the drawbacks, the Reppe process was for a half century the preferred process for EDO, but now the growth in EDO is being taken by the propylene oxide (PO) and butane feedstock routes. 

In summary, pyrolysis is a tertiary recycling process that is used to break down large polymer molecules. In this process, the polymer samples are heated in an inert atmosphere, which causes the carbon-carbon bonds to break along the polymer backbone. This depolymerization step results in monomers (short-chained compounds) being formed. Generally, three types of products are formed from pyrolysis reactions gas, oil and char. All three have the potential to be nsed as a fnel or chemical feedstock. Depending on the feed polymer and the reaction conditions, different products can be obtained. The pyrolysis oil can either be used directly or can be nsed as a raw material for the petroleum industry [1-5]. 

Research efforts are geared to developing oUs that meet changing food, feed, and chemical feedstock needs. Hundreds of fatty acids are produced in plant sources, and hundreds more are produced in organisms from microbes to mammals. Some of these would be of great value if they were available in suitable amounts from a crop source. The two general transgenic approaches used to develop such sources are as follows ... 

The large-scale petroleum consumers are exploring ways to supplement the convenient liquid fuel and chemical feedstock aspects of a conventional petroleum resource. Coal could be used in this way since the known reserves of hard coal have an estimated life of more than 200 years. However, extraction of coal is generally more difficult, equipment to consume it directly is more complex, and efficient emission control is more complicated than for petroleum combustion. 

Propane, o-butane (boiling point -12°C, 11°F), and butane generally constitute this sample type and are used for heating and motor fuels and as chemical feedstocks (ASTM D-2597, ASTM D-2504, ASTM D-2505). 

Rejining A general term that includes processing of crude oils to give fuels such as gasoline, diesel and jet, lubricants, asphalts, waxes, and chemical feedstocks. 

This section describes batchwise fixed-bed adsorbers in which the adsorbent is replaced with fresh material, or removed and regenerated after it is exhausted, then reinstalled. Commercial examples include columns used for chemical feedstock purification, decolorizing solutions, and wastewater treatment. The goal is generally to employ material balance and rate equations to predict adsorber performance, possibly to analyze experimental data (e.g., breakthrough curves and temperature histories), to diagnose problems, or to assess properties or conditions. Unfortunately, various conditions often result in nearly identical behavior, so diagnosing causes may be difficult. 

Definition of Pyrolysis. The word pyrolysis has had some problems in definition, especially when applied to biomass. The older literature generally equates pyrolysis to carbonization, in which the principal product is a solid char. Today, the term pyrolysis is generally used to describe processes in which liquid oils are preferred products. This symposium was concerned with the latter pyrolysis - processes which offer enhanced yields of liquid oils, especially those with desirable chemical compositions and physical attributes for liquid fuels, fuel supplements and chemical feedstocks. 

Electrochemistry is clearly an important component of the technology of many quite diverse industries. Moreover, the future for electrochemical technology is bright and there is a general expectation that new applications of electrochemistry will become economic as the world responds to the challenge of more expensive energy, of the need to develop new materials and to exploit different chemical feedstocks and of the necessity to protect the environment. 

It can also be obtained by steam cracking of ethane at temperatures above 1200°C. Nowadays acetylene has generally been replaced by alkenes as a chemical feedstock. India and East European countries however, continue to use some acetylene technology as they have adequate coal reserves but are oil importers. 

Figure 1.11 Fossil energy requirement for petrochemical polymers and PLA. The cross-hatched area of the bars represent the fossil energy used as chemical feedstock (i.e., fossil resource to build the polymer chain). The solid part of the bars represented the gross fossil energy used for the fuels and operation supplies used to drive the production processes. PC = polycarbonate HIPS = high-impact polystyrene GPPS = general purpose polystyrene LDPE = low-density polyethylene PET SSP = polyethylene terephthalate, solid-state polymerization (bottle grade) PP = polypropylene PET AM = polyethylene terepthalate, amorphous (fiber and film grade) ...

---