Catalytic cracking with Zeolites process for liquid fuel preparation

from plastics, wastes, vegetable oils, animal fats and algae

Thermo-catalytic cracking plants are devices which are suitable for waste utilization. The essence of

their operation is that throughout a catalytic-cracking procedure oil is produced from e.g: plastic waste. Catalytic cracking – thermal decomposition in the presence of a catalyst - is more frequently used than

the pyrolysis. The benefit of catalytic cracking before the pyrolysis is then in lower working temperature, lowered up to 150 - 450 °C in comparison to pyrolysis. One method of catalytic cracking of plastics and wastes is to use zeolites as the catalysts. Zeolite catalysts are crystalline alumino-silcate materials based on a three dimensional network of AlO4 and SiO4 tetrahedrally linked through oxygen atoms. Zeolites are porous and contain dimensionally defined pores with regions of high electrostatic field associated with the presence of cations. These regions are catalytically highly reactive. Pore size can be altered according the requirements on the product. Synthetic zeolite catalysts ZSM-5 or HZSM-5 or catalysts MCM type (X and Y) are able to crack long-chain hydrocarbons. The drawback of this group of processes is high price of zeolite catalysts and their limited recyclability as well as the problems of the treatment with spent catalyst. On the other hand natural zeolites are cheap and it is not necessary to recycle them. The surface of a Zeolith-corn corresponds to that of a sponge with regular pores. The pore opening and the structure of the pores are characteristic for the respective zeolite type. Through this configuration has a Zeolithe a form of selectivity, which can be used as a molecular sieve and/or cracking catalyst. Every Zeolithe has characteristic pores and channels, together with the possibilities of surface modification the Zeolithes become an excellent heterogeneous catalyst. The cracking occurs at the acidic centres. Utilization of plastic and Rubber waste Rubber and plastic make up the special part of the organic wastes, practically as a not destroyable material. Their elimination cannot be solved with simple tools or burning, since the harmful effects of the free carbon particles (strong smoke), which damage the environment to a great extent, and the poisonous substances stuck on them are significant. The production of rubber is based on a polymerization chemical technology. Reversing and executing the process, with external energy, the substance having a great molecule falls apart into substances with smaller molecules. The shortly described depolymerization process, if it is maintained by heat energy then it is considered pyrolysis, supposing that the reaction space is kept hermetic. Part of the plastic wastes is renewable, but there is a part which cannot be reused due to production or other reasons, (polluted, etc) to which the above mentioned solution, like in case of rubber, can be applied, since plastics are fundamentally crude oil derivatives, with less carbon type filler. The plant works according to the principle of thermo catalytic cracking. The essence of the device is that the above mentioned slowly dissolving organic waste (rubber, plastic) after homogenizing (given 20-25 mm measure) grind, heated with external cape heating in an inside space strangulated from oxygen forwarded by pulley dosage, the waste arrives to the steam- and gas phase, and at the end of the process char is produced. The developing steam phase exiting from the device goes through a multi circle condensation system, through which the appropriate liquid phases are developed (similarly to the fractioned distillation process, however compared to the traditional distillation methods, under simpler and cheaper implementation circumstances).

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Throughout the procedure the following so called cracking products are produced:

• recycling-diesel , recycling-gasoline, water

• recycling-gas

• recycling-char, steel – in case of rubber waste

The catalytic cracking system has a block system, meaning that it can be built modularly with smaller and greater performance.

The benefits of catalytic cracking in comparison with other known processes can be formulated as

follows: 1. Catalytic cracking is not a new process. It is well known and is currently used in the petroleum and

petrochemical industry to convert high molecular weight components to lower molecular ones which can be used directly or blended for use as fuel. The main groups of catalysts used include transition metals, synthetic zeolites and molecular sieves, activated alumina. The drawback of this procedure, giving product with excellent fuel properties, is the need of expensive high-pressure technology in the hydrogen presence, expensive catalysts as well as the lowering catalyst activity.

2. The aim of WTS-technology is to work with a technology called catalytic cracking with zeolites.

Catalytic cracking with zeolites is a relatively simple process which takes place in simple pressure less apparatus inexpensive to construct. It can be processed also in small scale plants located near to raw material sources with minimum transportation costs.

3. There are no other reactants except the catalyst as it is for example by transesterification. The process

is cheap; it can utilize also low quality sources as municipal waste or oils/fats with high acid number, waste oils/fats, fatty acids, fatty acid methyl esters and algae. Process is not sensitive to the quality of input, also to blends of shown recourses; the product quality is practically independent on input parameters.

4. The yield of process is high; the share of liquid condensate represents 80 to 90 % wt (of the hydrocarbon content), besides about 5 % wt. of gaseous products and about 5 % wt. of char residue. There are no problematic wastes; the cracking residue can be used for energetic purposes or in metallurgic field (depending input materials).

5. The liquid condensate has similar properties to fossil fuels – gasoline and diesel fuel. The process can

be managed so that the portion of diesel fuel is over 70 % of liquid condensate. The gas can be utilized as the fuel to create the heat for the process. The heavy fraction is brown liquid with tolerable odour. Its viscosity is about 2,5 to 9 mm2/s at 40 °C, density about 805 to 900 kg/m3 at 15 °C, oxygen content about 12 to 15 % wt., water content about 500 to 900 ppm (depending water content of input material), acid number between 10 and 135 mg KOH/g, the heat of combustion about 39 to 41 MJ/kg. The comparison of GLC chromatogram of this heavy fraction and of fossil diesel one shows that the similar compounds in both materials is present but only from the point of view of volatility and not of chemical identity. As long as the fossil diesel is a mixture of saturated n-, iso-alkanes and cycloalkanes with aromates mainly alkyl benzenes, the heavy fraction contains mainly the unsaturated hydrocarbons and oxygenates in the form of aldehydes, ketones, alcohols and acids. Such treated liquid condensate can be used as a fuel component for diesel engines as a blend with fossil diesel fuel with which is mixable in every portion (ratio) at laboratory temperature.

6. In the case of catalytic cracking of Triacylglycerols, glycerol is not created. This component is decomposed into reactive compounds which predominantly react onwards and form a part of the final product and so increase the yield. 7. There gives two possibilities: - catalytic cracking with synthetic zeolite, high price app. € 2,5/kg, spent catalyst have to be

burned and used again regenerated (losses app. 2-3%), expensive process. - catalytic cracking with natural zeolite, low price app. € 0,25/kg, this can be left in char, inexpensive process.

8. Synthetic zeolites are sensitive to water, while some natural zeolites are not sensitive to water. 9. The type of input e.g. oil/fat affects the composition of liquid cracking condensate only in low measure. By Zeolithe-catalysts practically don’t exist limiting parameters for input oil/fat as acidity, humidity, presence of other matters and so on. In this way the used edible oils and a kafilery fats can be also utilized. 10. The WTS-process is running with a special activated natural zeolite. Photo of a pilot plant with a capacity of 250 kg/h solid waste

The higher the hydrocarbon content in the input material, the higher the yield of fuels. Cracking plant 500kg/h input solid waste

Scheme of a cracking plant

Type of reactor: screw conveyor indirect heated Reactor temperature: 380 - 420 °C Pressure: ambient to 7 mbar “Deparafination” at 360 °C (“paraffin” back to cracking process)

Mass balance from different wastes

The mass balances show the composition of products. GL-chromatogram - comparison fossil diesel fuel with recycling diesel (from cracking process municipal waste with activated natural zeolite catalyst)

Fossil diesel fuel – Recycling diesel

Input 100%

Gas 29,7%

char 28,3%

RCbenzin 10,3%

RCdiesel + schw. Frakt. 20,6%

H2O 10,8%

0,3% losses

Waste town Györ

Input 100%

Gas 21,5%

char 29,2%

RCbenzin 18,7%

RCdiesel + schw. Frakt. 21,2%

H2O 4,3%

0% losses

waste Umweltdienst Burgenland – Austria

Input 100%

Gas 10%

char 7,5%

RCbenzin 19,2%

RCdiesel + schw. Frakt. 58,2%

H2O 5%

0,1% losses

Plastic blend 70%PE, 25%PP, 5%PVC

Input 100%

Gas 11%

char 9,5%

RCbenzin 21,2%

RCdiesel + schw. Frakt. 51,1%

H2O 7%

0,2% losses

Plastic blend 43%PE, 35%PP, 6%PS, 5%PET, 8%ABS, 3%P VC

Input 100%

Gas 12%

char 40%

RCbenzin 16,6%

RCdiesel + schw. Frakt. 24,1%

H2O 7%

0,3% losses

Input 100

Gas 12%

char 33%

RCbenzin 18,8%

RCdiesel + schw. Frakt. 31,1%

H2O 5%

0,1% losses

Shreddered waste tires Shredded rubber , inner tube from tire

The chromatograms are virtually identical. They have the same boiling points, but they have not the same chemical composition.

Conclusion It is possible to produce lower-grade feedstock (such as residual waste), high-quality fuel or fuel. The obtained RC-diesel products are higher in density and viscosity as recorded in the standard E 590. The comparative GLCS are almost identical with those of fossil diesel. The flash point is between fossil diesel and bio diesel. The expected amounts of RC-diesel from 9 to 70 % (depending on the plastic content of the input material) should be regarded as sufficient. The proportion of 6 to 20 % of RC-gasoline also provides an interesting magnitude. The resulting RC-gas with a share of 10 to 30% has been successfully tested on several gas motors. The methane content (30 to 45% of RC-gas output) provides a satisfactory magnitude. Other hydrocarbon compounds are of minor size. The lower heating values of oil cracking (RC-diesel RC-gasoline) from 39.2 to 40.4 MJ / kg (fuel oil from 38.9 to 42.6 MJ / kg) and the gas from 40.6 to 42.5 MJ / kg (natural gas from 32.4 to 45 MJ / kg) correspond to those of fossil origin. Catalytic cracking with natural zeolite is a low price process with excellent products. The special activated natural zeolite from World Technical Solution Kft. is not sensitive to water and is fully usable for processing wastes “earning” from ocean without drying before (only simple pressing).. Bratislava, 2.11.2011 DI. Eduard Buzetzki