Smuda process

Nickel silicate and ferrous silicate are the preferred catalysts in the Smuda process. The Smuda catalyst is a layered silicate clay framework with ordered nickel (or iron) atoms inside. The catalyst is charged at 10 wt% ratio of the plastic feedstock. The catalysts are based on layered silicates with Lewis acid activity [24]. Catalytic cracking results in very little noncondensable gas ( 1%) and minimal carbonaceous char. The hfe of the Smuda catalyst is approximately 1 month [24]. 

Natural minerals and ores containing transition metal ions, steehnaking slags or metal plant wastes can be used as catalysts or sensitizers in the plastic material cracking. These materials include Ni203, NiO, Fe204 and C02O3. 

A number of low-grade transition metal ores (for example, minerals containing nickel oxides) can be used as catalysts. Smuda has demonstrated that microwave or radiofrequency irradiation of a mixture of such ores with a carbon source initiates reduction of the oxide to metal. With this approach, poisoning the active sites of the catalyst will not be critical for the process since there will be a constant supply and generation of active catalyst with the feed material. In addition to well-known catalytic properties of nickel in organic reactions, it was also shown that Ni on carbon and other supports, catalyzes hydrodechlorination and dehydrochlorination of chlorinated organic waste streams [22-24], 

The Smuda process also uses new cracking catalysts based on cobalt resinates which are cobalt salts of resin acids (mainly abietic acid) such as cobalt abietate and cobalt linoleate (these are commonly referred to as driers in the coatings industry) and preferably with admixtures of heavy metal silicates. Smuda has also explored the use of manganese resinate deposited on an aluminium oxide support to maximize active surface area [23]. 

In the Smuda process the pyrolysis reactor temperature is 350°C and the operating pressure is 4-5 psi. The pyrolysis gases from the pyrolysis vessel are sent directly to a distillation column. The distillation column has a typical temperature profile as follows top 140°C, Sulzer 250Y middle 322°C, Sulzer 350Y and bottom 331°C. 

---

Carbon residue may be present in the diesel fuel in suspended form. The carbon residue can be removed by ultracentrifuging. In the Smuda process some of the light layered clays can be carried out of the pyrolysis vessel with the hot pyrolytic gases and can be entrained in the condensed fuel. 

Due to the sensitivity of the catalyst, the Smuda process requires that the plastic feedstock be pre-processed and cleaned by mechanical processing (i.e. other than washing). In this way dirt, food impurities, etc. can be removed before they deactivate the catalyst [24]. 

Advantageously, the Smuda Process can tolerate high levels of PET. In catalytic pyrolysis the terephthalic acid is decarboxylated to give benzoic acid and benzoates [24] (see also Figure 15.3). PET gives fuel with appreciable aromatic content (e.g. level of 10% or higher). In other competitive processes PET proves problematic due to the formation of troublesome terephthalic acid (TPA) deposits in the downstream pipework and condensors. 

The Smuda process uses a reflux return where longer paraffin chains that condense shortly after exiting the main chamber are allowed to flow back to the main chamber (the reflux effect ). Also the heavies from the bottom of the distillation column flow back to the pyrolysis chamber for re-cracking (Figure 15.10b). 

The diesel fuel has 10% a-olefin content (i.e. terminal unsaturation or double bonds) which make the fuel unstable and prone to polymerization (i.e. sludge formation). There is no proven track record for producing transportation-grade diesel from the Smuda Process (Poland plant produces crude oil from plastics which is subsequently sent to a refinery). 

Smuda A process for pyrolyzing waste plastics (preferably polyolefins) with the production of diesel fuel and gasoline. A disposable catalyst is used, preferably nickel silicate. Developed by H.W. Smuda (also spelled Zmuda). A large plant has operated in Zabrze, Poland, since 1997. 

Michigan Technological University used ammonium hydroxide to directly form the diammonium salt of TA [221]. Schwartz used sodium hydroxide in solution, which was heated to depolymerise and distil off EG, the residue being mixed with water, filtered and acidified to recover TA [222, 223]. Institut Francais de Petrole also used sodium hydroxide, but in this case in the melt, preferably in an extruder [224]. Smuda used bicarbonates rather than hydroxides [225], as has also featured in patents from Tsukishima Kikai [226, 227]. Tredi used alkali metal hydroxides in a process in which pure salt is recovered [228]. Broccatelli mixed scrap PET bottles along with metal salt such as sodium carbonate in a grinder, followed by dissolntion of salts formed in this crude reaction [229, 230]. 

---