Sulfur catalyst regeneration

If a waste sulfuric acid regeneration plant is not available, eg, as part of a joint acrylate—methacrylate manufacturing complex, the preferred catalyst for esterification is a sulfonic acid type ion-exchange resin. In this case the residue from the ester reactor bleed stripper can be disposed of by combustion to recover energy value as steam. 

Boron trifluoride catalyst may be recovered by distillation, chemical reactions, or a combination of these methods. Ammonia or amines are frequently added to the spent catalyst to form stable coordination compounds that can be separated from the reaction products. Subsequent treatment with sulfuric acid releases boron trifluoride. An organic compound may be added that forms an adduct more stable than that formed by the desired product and boron trifluoride. In another procedure, a fluoride is added to the reaction products to precipitate the boron trifluoride which is then released by heating. Selective solvents may also be employed in recovery procedures (see Catalysts,regeneration). 

Fluid catalyst regenerator Fuel gas combustion Claus sulfur recovery TRS X Storage tanks... 

Compounds considered carcinogenic that may be present in air emissions include benzene, butadiene, 1,2-dichloroethane, and vinyl chloride. A typical naphtha cracker at a petrochemical complex may release annually about 2,500 metric tons of alkenes, such as propylenes and ethylene, in producing 500,000 metric tons of ethylene. Boilers, process heaters, flares, and other process equipment (which in some cases may include catalyst regenerators) are responsible for the emission of PM (particulate matter), carbon monoxide, nitrogen oxides (200 tpy), based on 500,000 tpy of ethylene capacity, and sulfur oxides (600 tpy). 

FCC units, and in particular the catalyst regenerating section, may give rise to significant pollution. Sulfur in the coke oxidizes to SO2 and SO3, while the combustion also generates NOx compounds. In addition, the flue gas from the regenerator contains particulate matter from the catalyst. The FCC process is also the major source of sulfur in gasoline. Of all the sulfur in the feed, approximately 50% ends up as H2S in the light gas-LPG fraction, 43% in the liquid products and 7% in the coke on the spent catalysts. 

Sulfurized and sulfurchlorinated unsaturated compounds and mercaptans are used as lubricant additives (antiwear, friction modification, load-carrying, extreme pressure and temperature, corrosion inhibition, and antioxidants), refinery catalyst regeneration compounds, steel processing (annealing) aids, and vulcanization catalysts (see Lubrication and lubricants). 

Presulfide—A step in the catalyst regeneration procedure which treats the catalyst with a sulfur-bearing material such as hydrogen sulfide or carbon bisulfide to convert the metallic constituents of the catalyst to the sulfide form in order to enhance its catalytic activity and stability. 

Regeneration is a critical step in catalytic reformer operation to regain activity, selectivity and stability of deactivated catalyst. Regeneration procedures and capabilities are dependent on the causes of deactivation. The procedures are proprietary in nature and supplied by catalyst vendors or process licensors The catalyst deactivated by coke can be easily regenerated to restore it s activity, Modified methods are adopted when catalyst had suffered from sulfur or water upset. It is important to emphasize that on line catalyst samplers are good tools to know the state of catalyst, causes of deactivation and help in improving operational and regeneration effkiency[ll]. There are no samplers installed in the reformer under discussion... 

Katzer, J. R., AES and Reaction Studies of Poisoning by Sulfur and Regeneration of Metal Synthesis Gas Catalysts. Annual Report submitted to the U.S. Department of Energy under Contract No. E(1 l-l)-2579, January, 1978. 

In this project, the feasibility of catalyst regeneration by supercritical fluid extraction was studied. A spent catalyst from an industrial naphtha hydrotreater was extracted with tetrahydrofuran, pyridine, carbon dioxide, and sulfur dioxide under subcritical and supercritical conditions. The coke reduction and changes in the catalyst pore characteristics were measured and to a limited extent the catalyst activity was evaluated. It is shown that by supercritical extraction, the coke content of spent hydrotreating catalysts can be reduced and the catalyst pore volume and surface area can be increased. 

The relatively high Si/Al content of mordenite confers on it a certain acid stabihty that enables it to be used to remove water from acid gas streams such as reformer recycle hydrogen, reformer catalyst regeneration gas, HCl, CI2, and chlorinated hydrocarbons. It can also be used to treat off-gas for removal of oxides of sulfur and nitrogen (SO and NO ). Mordenite s ion-exchange selectivity for Cs has been used to remove Cs radioisotopes from nuclear waste (Zeolon 900) and it is used in Japan on a plant scale to separate gases from the air. 

Supported metal catalysis are employed in a variety of commercially important hydrocarbon conversion processes. Such catalysts consist, in general, of small metal crystallites (0.S to 5 nm diameter) dispersed on non-metallic oxide supports. One of the major ways in which a catalyst becomes deactivated is due to accumulation of carbonaceous deposits on its surface. Catalyst regeneration, or decoking, is normally achieved by gasification of the deposit in air at about 500°C. However, during this process a further problem is frequently encountered, which contributes to catalyst deactivation, namely particle sintering. Other factors which can contribute to catalyst deactivation include the influence of poisons such as sulfur, phosphorus, arsenic and... 

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