Markings, recycled products

Recycling marks on products (Fig. 1.11) allow the common plastics to be identified (Table 1.1). Sometimes numbers are used in place of the abbreviation for the polymer name. 

Recycling of the ligands was investigated for ligands D, E and J. over four recycles the conversions dropped for all three phosphites, however the most marked decrease was with E (<10% conversion in the fourth recycle). The selectivity of the catalysts to aldehyde products did not decrease so drastically but a decrease in the selectivity of E was most notable in the second recycle. This suggests that some leaching of the three phosphites to the organic phase does occur. 

In 1975, the total world tin production was 236,000 tons, of which 72% was produced by China (10%), Indonesia (8%), Malaysia (35%), Thailand (7%), and 6% each by the U.K. and the former Soviet Union (WHO 1980). Annual mine production of tin in the United States is a comparatively low 3300 metric tons (USPHS 1992). The world production of recycled tin was about 20,000 tons, of which France produced about half (WHO 1980). About 25% of the tin used in the United States is recovered from scrap materials containing tin. This secondary production occurs in the United States at 7 detinning plants and 162 processing plants (USPHS 1992). The production and consumption of tin chemicals, especially organotins, has increased markedly in the past several decades (Table 8.2). 

Independent conversion processes may not employ the Claus reaction for sulfur production and do not recycle the captured sulfur compounds to the Claus plant. Examples are the Beavon Mark I Process (Hydrogenation + Stretford) (13), the Beavon Mark II Process (Hydrogenation + Claus) (13), and the SNPA/Haldor-Topsoe Process (Catalytic Oxidation to SOi.) (9,10). 

Table V shows the salient features of several Fischer-Tropsch processes. Two of these—the powdered catalyst-oil slurry and the granular catalyst-hot gas recycle—have not been developed to a satisfactory level of operability. They are included to indicate the progress that has been made in process development. Such progress has been quite marked in increase of space-time yield (kilograms of C3+ per cubic meter of reaction space per hour) and concomitant simplification of reactor design. The increase in specific yield (grams of C3+ per cubic meter of inert-free synthesis gas) has been less striking, as only one operable process—the granular catalyst-internally cooled (by oil circulation) process—has exceeded the best specific yield of the Ruhrchemie cobalt catalyst, end-gas recycle process. The importance of a high specific yield when coal is used as raw material for synthesis-gas production is shown by the estimate that 60 to 70% of the total cost of the product is the cost of purified synthesis gas.

The downflow fixed-bed reactor has been used widely for hydrodesulfurization processes and is so called because of the feedstock entry at the top of the reactor while the product stream is discharged from the base of the reactor (Figure 5-6). The catalyst is contained in the reactor as stationary beds with the feedstock and hydrogen passing through the bed in a downward direction. The exothermic nature of the reaction and the subsequent marked temperature rise from the inlet to the outlet of each catalyst bed require that the reaction mix be quenched by cold recycle gas at various points in the reactor. Hence the incorporation of separate catalyst beds as part of the reactor design. 

To a plastic producer (i.e. processor), melt index is one property that is needed in order to evaluate whether the same process can be used irrespective of whether it uses virgin or recycled polymers. This will tell if it is possible to process the recycled polymeric materials in the same set-up as usual. Several other properties are needed in order to quality mark the materials. The melt index is related to what final tensile properties a product obtains, this in turn has an impact on the expected life-time. The purity of a recyclate stream with respect to the amount of foreign polymer in the stream has an impact on melt-index, but will also be an important factor for the final mechanical properties. Another very important property is the amount of low molecular weight compounds, which may be of vastly different types. Typically such an analysis will show the presences of additives and their degradation products, degradation products of the polymeric matrices, traces of solvents, initiators, or catalysts, compounds related to the use of the plastics and others. 

Probably the most important step in the LCA is the inventory analysis, which carefully documents the (raw) materials necessary for the product, the emissions, required energy input and environmental burden at disposal by either recycle, disposal, etc. Here it is very useful to clearly mark the system boundaries. ISO 14040 [1] defines inventory analysis as follows ... 

The double slush technique offers added service value, such as ageing resistance, passive safety, weight savings and the recycling of production waste in the same application. The Audi A2 now marks the first production car to have come onto the market with an instrument panel surface developed according to this technology. 3 refs. Translated form Kunstoffe Vol.90 No.3, 2000, p.114-7. 

The combined features of charge and catalyst stabilisation find their expression in markedly enhanced recyclability. Using catalyst loadings of 2.5 - 5 mol%, the activity decreased by only a few percent after 10 cycles and remained above 90% of the initial value. Furthermore, the catalyst solution could be kept for months without measurable loss in activity. By substituting the tricyclohexylphosphine ligand for a A -heterocyclic carbene, catalyst stability was further improved which finds its expression in very low residual ruthenium levels in the isolated product.[44] As these are only the... 

The waste plastics utilized at the SPR plant are the household waste plastics specified by the Containers Packaging Recycling Law and marked as recyclable on the each of the products. The waste plastics are discharged at curbside by residents once per week, and collected, sorted, compacted in bale form by the local government, which then snpplies the SPR plant. 

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