Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J38/00—Regeneration or reactivation of catalysts, in general
  • B01J38/48—Liquid treating or treating in liquid phase, e.g. dissolved or suspended
  • B01J38/60—Liquid treating or treating in liquid phase, e.g. dissolved or suspended using acids
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/34—Chemical or biological purification of waste gases
  • B01D53/96—Regeneration, reactivation or recycling of reactants
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
  • B01J27/14—Phosphorus; Compounds thereof
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J38/00—Regeneration or reactivation of catalysts, in general
  • B01J38/48—Liquid treating or treating in liquid phase, e.g. dissolved or suspended
  • B01J38/60—Liquid treating or treating in liquid phase, e.g. dissolved or suspended using acids
  • B01J38/62—Liquid treating or treating in liquid phase, e.g. dissolved or suspended using acids organic

Definitions

• the invention relates to a process for the regeneration of phosphorus-loaded Denox catalysts.
• the denitrification is carried out in parallel, with nitrogen monoxide being reacted with ammonia and atmospheric oxygen to form elemental nitrogen and water, or nitrogen dioxide also reacting with ammonia and atmospheric oxygen to form elemental nitrogen and water.
• This reaction requires catalysts called denox catalysts. These are catalysts of various shapes such as those with a glass fiber body or honeycomb or plate catalysts based on titanium dioxide, which contain the oxides of various transition metals such as vanadium, molybdenum or tungsten as active components.
• such catalysts leave after hours of operation, for example in the Order of magnitude of 30,000 hours in terms of its effectiveness, which is due on the one hand to the clogging or blockage of the passages by fly ash, and on the other hand to the formation of barrier layers by the ammonium sulfate formed in the course of denitrification by residual ammonia and also by poisoning of the active ones Centers through elements or compounds contained in the exhaust air such as arsenic, phosphorus, etc.
• a special problem is the reduction in performance of Denox catalysts by means of phosphorus compounds.
• Coal as a fuel must be taken into account that coal, depending on its age and origin, can have a not inconsiderable amount of mineral constituents, some of these compounds acting as catalyst poisons such as iron, arsenic, phosphorus, thallium, antimony, chromium etc.
• the phosphorus content elementary or in the form of
• 'Phosphorus pentoxide can, based on the total amount of the mineral components of the coal in the range of about 0.5 to 1 weight
• Phosphorus compounds that are in the flue gas not only settle mechanically on the surfaces of the catalytic converter, but also undergo chemical reactions with the active constituents and thus lead to a reduction in the performance of Denox catalysts.
• a process is therefore proposed in which the catalyst is first treated with an aqueous solution of alkali from the group of alkaline earths, ammonium or organic amines and then with an aqueous solution of an inorganic or organic acid.
• the catalysts to be regenerated come from different power plants that use coal of different origins and quality as fuel, an analysis of the chemical composition of the catalyst and its degree of contamination is absolutely necessary before regeneration. Based on the analysis values and the content of interfering phosphorus compounds, it is readily possible for the person skilled in the art to determine the required concentrations of reaction liquids and possibly pre-treatment and post-treatment steps in advance and to adapt them to the respective situation.
• catalysts which have to be regenerated have a high dust load, so that mechanical pretreatment for removing fly ash from the catalyst surfaces or passages, for example by using industrial vacuum cleaners or compressed air, has mostly proven to be necessary.
• the catalysts have a strong barrier layer of salts such as ammonium sulfate, which is formed by the reaction between SO 3 and the so-called ammonia slip, treatment with water can also be carried out in order to detach these barrier layers.
• the catalysts are then introduced into a reaction solution which is essentially an aqueous solution of an inorganic or organic base.
• a reaction solution which is essentially an aqueous solution of an inorganic or organic base.
• strong bases for the regeneration of catalysts such as caustic soda or potassium hydroxide is known per se, but here it has surprisingly been found that the elimination of phosphorus compounds can best be accomplished by using medium-strong bases.
• Oxides or hydroxides of alkaline earth metals or ammonium hydroxide or organic bases with a pk value between about 2.5 to 5.5 are therefore preferably used.
• alkaline salts such as carbonates, tartrates, oxalates, acetates etc. can also be used, the choice of the compound used being determined by its water solubility and the cost of such a product.
• the catalysts are subjected to an acid treatment in a further step in order to remove excess alkali and to activate the catalytically active centers of the catalyst.
• Inorganic acids such as phosphoric acid, sulfurous acid or organic acids such as formic acid, acetic acid, chloroacetic acid, citric acid, oxalic acid, tartaric acid or benzenesulfonic acid or sulfanylic acid are preferably used as acids, the choice again essentially depending on the availability and the cost of such compounds.
• Surfactants are preferably added to both solutions in order to improve the wettability of the catalyst surfaces and the penetration of the reaction liquids into the pores of the catalyst.
• the addition of anionic, cationic, amphoteric, nonionic or zwitterionic surfactants is generally in the range between 0.01 to 0.1% by weight, based on the total solution.
• the catalyst module When carrying out the process, the catalyst module is immersed in the reaction solution, possibly after mechanical pre-cleaning, in which it can remain for a period of from 5 minutes to about 24 hours, depending on the degree of contamination and additional treatment.
• the temperature of the solution which in principle can be between ambient temperature and higher values up to 100 ° C., can be increased, preferably to 60 ° C.
• the treatment time can be shortened for both the alkaline and the acidic reaction solution and the effectiveness of the treatment can be increased by either the catalyst module itself is moved or that the reaction liquid is moved regularly, the latter can be accomplished in a simple manner by agitators or submersible pumps. If the catalytic converter is to be moved, this should preferably be done in the longitudinal direction of the channels in the honeycomb catalytic converter or in the longitudinal direction of the plates as a lifting movement, which can be generated, for example, by attaching the module to a crane and moving it accordingly.
• the processing time can be further shortened by exposing the module to low-frequency vibrations of the reaction liquids or ultrasound, the low-frequency range being in the range from 50 to 1000 Hz and the frequency of the ultrasound being 10,000 to 100,000 Hz, preferably 20,000 to 50,000 Hz.
• the treatment with ultrasound leads to a local wave movement of the liquid on the catalyst surface and to the formation of cavitations, by the detachment of any barrier layers still present and the detachment of phosphorus and other compounds from the ceramic and thus the exposure of active centers.
• a three-part process has proven to be a particularly favorable working variant, in which the catalyst module is subjected to a primary treatment with the alkaline reaction liquid, advantageously with movement of the module or the surrounding liquid and advantageously with lifting or stirring movements, and the module is then transferred to an ultrasound tank being immersed in a reaction solution of the same composition and sonicated. Depending on the degree of contamination, the contaminated reaction liquid in the first tank can then either be used further or cleaned by filtration. After the ultrasound treatment, the catalyst module is removed from the sonication pool and into one immersed another basin with acid solution and again moved here, if necessary together with the reaction liquid, which can also be moved. The module is then rinsed several times with water and finally dried, for example by hot air at 50 to 400 ° C.
• transition metal oxides acting as activators or active centers are soluble to a certain degree in both alkalis and acids, a further analysis should be carried out at the end of the treatment to determine the content of transition metals. If the discharge has led to a reduction in the content of transition metals during the regeneration, a subsequent impregnation to the desired content can be carried out immediately by adding an appropriate aqueous solution and then drying.
• Example 1 The fly ash-free catalyst with a phosphorus content of 3 g / kg is adjusted to a 1.5 n (NH 4 ) 2 CO 3 solution with a surfactant additive at a temperature of 20 ° C.
• the reaction solution is pumped into the container by means of a submersible pump.
• the catalyst remains in the reaction solution container for 15 hours. After the reaction time, the catalyst is removed from the container and further treated.
• the fly ash-free catalyst with a phosphorus content of 5 g / kg is placed in a 2.0 n (NH) 2 CO 3 solution with added surfactant at a temperature of 60 ° C.
• the catalyst remains in the reaction solution container for 0.5 hours. After the reaction time, the catalyst is removed from the container and further treated.
• the fly ash-free catalyst with a phosphorus content of 5 g / kg is placed in a 2.5 N ammonium carbonate solution with added surfactant at a temperature of 20 ° C.
• the reaction solution is pumped into the container by means of a submersible pump.
• the catalyst remains in the reaction solution container for 15 hours. After the reaction time, the catalyst is removed from the container and further treated.
• the fly ash-free catalyst with a phosphorus content of 5 g / kg is placed in a 2N calcium acetate solution at a temperature of 60 ° C set.
• the catalytic converter is moved through a lifting mechanism
• Water preferably as a cascade rinse, is rinsed and then dried with hot air.
• the fly ash-free catalyst with a phosphorus content of 5 g / kg is placed in a saturated calcium hydroxide solution at a temperature of 60 ° C.
• the catalytic converter is moved by a lifting mechanism in the container.
• an ultrasound treatment with an energy density of 3 W / 1 takes place.
• the catalyst remains in the reaction solution container for 0.3 hours.
• the catalyst modules are removed from the reaction basin and immersed in an aqueous neutralization bath which contains oxalic acid.
• the catalyst module remains in this neutralization solution for 2 hours.
• the catalyst is then rinsed several times with water, preferably as a cascade rinse, and then dried with hot air.
• the catalyst freed from fly ash and containing 5 g / kg of phosphorus, is placed in a 2N ammonium carbonate solution at a temperature of 20 ° C.
• the catalyst remains in the reaction solution for 15 hours.
• the reaction solution is pumped into the container by means of a submersible pump.
• the catalyst is then placed in a 2N ammonium carbonate solution at a temperature of 60 ° C.
• the The catalyst is moved by a lifting mechanism in the container.
• the catalyst modules are removed from the reaction basin and immersed in an aqueous neutralization bath which contains oxalic acid.
• the catalyst module remains in this neutralization solution for 2 hours.
• the catalyst is then rinsed several times with water, preferably as a cascade rinse, and then dried with hot air.
• the catalyst is introduced into an aqueous solution of a vanadium salt containing 6.75 g / l vanadium at a temperature of 20 ° C. and remains there for 0.5 hours.
• the catalyst is then dried with hot air.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Biomedical Technology (AREA)
• Environmental & Geological Engineering (AREA)
• Health & Medical Sciences (AREA)
• Analytical Chemistry (AREA)
• Life Sciences & Earth Sciences (AREA)
• Oil, Petroleum & Natural Gas (AREA)
• Sustainable Development (AREA)
• Materials Engineering (AREA)
• Organic Chemistry (AREA)
• Catalysts (AREA)
• Exhaust Gas Treatment By Means Of Catalyst (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)

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• 2002
  • 2002-09-11 DE DE10242081A patent/DE10242081A1/de not_active Ceased
• 2003
  • 2003-09-10 KR KR1020057004278A patent/KR100711236B1/ko not_active IP Right Cessation
  • 2003-09-10 AU AU2003271596A patent/AU2003271596A1/en not_active Abandoned
  • 2003-09-10 EP EP03753403A patent/EP1536878A1/de not_active Withdrawn
  • 2003-09-10 WO PCT/EP2003/010042 patent/WO2004026447A1/de not_active Application Discontinuation
  • 2003-09-10 CA CA2496693A patent/CA2496693C/en not_active Expired - Fee Related
  • 2003-09-10 JP JP2004537029A patent/JP2005537929A/ja active Pending
  • 2003-09-10 CN CNB038217120A patent/CN100404110C/zh not_active Expired - Fee Related
  • 2003-09-10 US US10/527,512 patent/US20060135347A1/en not_active Abandoned
• 2011
  • 2011-03-25 US US13/072,405 patent/US20110172083A1/en not_active Abandoned

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