ES2390730B2 - CATALYTIC SYSTEM FOR THE COMBUSTION OF CLORATED VOLTAGE ORGANIC COMPOUNDS. - Google Patents

Abstract

The present invention relates to a catalytic system for the combustion of organochlorine volatile compounds of the formula: #Ce {sub, x} Pr {sub, 1-x} O {sub, 2} # where x is greater than or equal to zero and less than or equal to one.

Description

KATATIC SYSTEM FOR THE COMBUSTION OF CLORATED VOLTAGE ORGANIC COMPOUNDS

paint and enamel formulations.

1,2-dichloroethane (DCE, C2H4Cld is probably the most important chlorinated COY emitted in the waste streams of chemical plants, since it is used massively in the production of polyvinylchloride, a plastic material whose world production is only exceeded by that of polyethylene Although the industrial scale process has reached its technological maturity, residual amounts of this compound appear in the output stream that must be properly managed Other less frequent uses of the DCE are as a solvent in the cleaning of textile garments, parts degreaser

of emission source (waste gases from chemical plants, soil decontamination and water, solvent evaporation processes, etc.). Specifically, organochlorine compounds constitute one of the most stable, dangerous and frequently used groups of VOCs in the

they have a great variety both in their chemical nature (including aliphatic, aromatic, oxygenated and halogenated compounds) and

more stringent with respect to the permitted levels of atmospheric emissions. In particular, the emission of volatile organic compounds (VOCs) causes a significant environmental impact. These pollutants participate appreciably in numerous atmospheric processes that can cause harmful effects on human health. For example, it is known that VOCs are involved in the destruction of the ozone layer and often act as greenhouse gases. In addition, numerous VOCs have notable toxic effects in humans.

dispersant of plastics and elastomers and chemical agent in Currently there are cerium-praseodymium catalysts for the combustion of volatile organic compounds. However, when it comes to oxidation of

The patent addresses the treatment of gaseous streams that have small concentrations of DCE, compounds that have been selected as a model due to their majority presence in chemical plants and their high toxicity.

This scenario shows that the design of catalysts with optimal performance, in terms of activity and durability, offers new possibilities in the field of applied research. The present patent focuses its interest in the development and novel application of mixed cerium and praseodymium oxide catalysts in the control of chlorinated VOC emissions.

The catalysts used to a greater extent for this environmental application contain as active phase noble metals, which exhibit a high oxidation efficiency but with a very high cost. In addition, generally, these types of catalysts gradually lose their activity in the presence of chlorine in the reaction medium. As an alternative, catalysts based on transition metals appear which, although less active, are more economically affordable and more stable and durable.

Compliance with the legislation related to VOC emissions requires significant improvements in the efficiency of purification technologies. In recent years the reduction of atmospheric levels through combustion or oxidation its ability to destroy compared to thermal and a consequent reduction in the formation of secondary as nitrogen oxides. In practice, those in contact with a catalyst should show a high intrinsic activity to the

A chlorinated volatile organic compound, most of these oxidation catalysts are deactivated in a very short time when they are poisoned with chlorine, and stop working.

In a more particular aspect of the present invention, the volatile compound is 1,2-dichloroethane.

In a second aspect, the present invention relates to a combustion process of organochlorine volatile compounds characterized in that it uses a catalytic system as described in the present invention.

In a more particular aspect, the catalyst mass of the present invention must be greater than 0.85 g to treat a current of 500 cm3 / min of a gas with a concentration of 1000 ppm of organochlorine compounds.

In a more particular aspect, the particle size of the catalyst of the present invention is between 0.3 and 0.5 mm.

In a more particular aspect of the present invention, x is selected from 0, 0.2, 0.5, 0.8 or 1.

where x is greater than or equal to zero and less than or equal to one.

Thus, in a first aspect, the present invention relates to a catalytic system for the combustion of volatile organochlorine compounds of the formula:

The present invention provides a catalytic system for the combustion of volatile organochlorine compounds that solves the problems described in the state of the art.

Description of the invention

For the therefore, there is a need for a catalyst for combustion not to deactivate rapidly with the

Figure 6 shows the analysis by X-ray photoelectronic spectroscopy (XPS) of the amount of surface chlorine that the catalysts contain after the combustion of 1,2-dichloroethane as a function of the nominal amount of praseodymium that each oxide contains. (Circles: after three catalytic cycles heating from 150ºC to 500ºC; Square: after 120 hours of catalytic combustion at 325ºC).

Figure 5 shows the Raman spectra of the fresh catalysts (a) and used in three consecutive cycles of 1,2-dichloroethane catalytic combustion tests conducted between 150 and 550 ° C (b).

Figure 4 represents the X-ray diffractograms (DRX) of the fresh catalysts (a) and used in three consecutive cycles of 1,2-dichloroethane catalytic combustion tests carried out between 150 and 550 ° C (b).

shows the catalytic combustion test of 1,2-dichloroethane carried out with the Ce50Pr50 catalyst at 325 ° C for 120 hours.

Figure 2 shows the results obtained in three consecutive cycles of 1,2-dichloroethane catalytic combustion tests carried out between 150 and 550 ° C. (T50% is the temperature at which 50% of the hydrocarbon is oxidized).

Figure 1 shows the 1,2-dichloroethane catalytic combustion tests performed with fresh (freshly prepared) catalysts between 150 and 550 ° C.

Description of the graphics

In a fourth aspect, the present invention relates to the use of a catalyst as described in the present invention for the treatment of gaseous streams containing 1,2-dichloroethane.

In a third aspect, the present invention relates to the use of a catalyst, in this document, for the control of emissions in a more particular aspect, for the

Detailed Explanation of the Invention

Example 1: Preparation of the catalysts Five catalysts were prepared with the general formula CexPr1-X02 where x = 1,

They were active than cerium rich. In addition to the activity, it was essential to analyze the stability of each catalyst, so three cycles of consecutive experiments were performed with each catalyst similar to those shown in Figure 1.

Figure 1 shows the conversion curves of 1,2-dichloroethane as a function of the reaction temperature for the different catalysts prepared. As a general trend it was observed that the catalysts rich in praseodymium

-Catalyst mass: 0.85 g Space speed: 30000 h-1

-

1,2-Dichloroethane concentration: 1000 ppm

-

Air flow: 500 cm3 / min

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Reaction temperatures between 150-500 ° C

-

Catalyst particles size 0.3-0.5 mm

Example 2: Combustion tests of 1,2-dichloroethane Catalytic combustion tests of 1,2-dichloroethane were performed in a fixed bed reactor coupled to a gas chromatograph with FIO detectors, TCO and ECO using the following reaction conditions:

Pr (N03hquot; 6H20, from Sigma Aldrich, 99.9%) was dissolved in water and The hydroxides precipitated / co-precipitated by adding ammonia to achieve pH = 9. The precipitates were filtered, dried and calcined at 500 ° C.

0.8, 0.5, 0.2 AND O. The nomenclature used to refer to catalysts it is Ce1 Pr1 00, respectively. The 3hquot; 6H20 of Aldrich, 99% and

Figure 2 shows the temperature at which each catalyst reached 50% conversion of 1,2-dichloroethane (parameter T50% (ºC)) for each of the reaction cycles. Most of the catalysts were deactivated in greater

All fresh catalysts (Figure 4a), regardless of their composition, showed a characteristic diffraction pattern of a type structure After catalytic tests (Figure 4b), catalysts with cerium contents between 50 and 100% (Ce50Pr50, Ce80Pr50 and Ce100) they continued to show the characteristic diffraction pattern of fluorite, while catalysts with high praseodymium content (Pr100 and Ce20Pr80) showed a diffraction pattern attributable to the PrOCI compound. This indicated that these catalysts incorporate IC into their structure during the catalytic tests, explaining the severe deactivation they experienced. It is interesting to note that the Pr100 catalyst, which was the one that suffered the most deactivation, was also the one that showed the best defined PrOCI diffraction peaks.

The X-ray diffractograms of fresh catalysts (Figure 4a) and used in three consecutive cycles of 1,2-dichloroethane catalytic combustion tests (Figure 4b) performed between 150 and 550 ° C are presented in Figure 4.

Example 3: Characterization of fresh and used catalysts.

The best catalyst (Ce50Pr50) was selected to perform a catalytic combustion test of 1,2-dichloroethane at 325 ° C for a very long time, in order to analyze in depth the stability over time. In Figure 3 it is observed that the activity of the catalyst was kept constant during the 120 hours that the experiment was prolonged, confirming its great stability under reaction conditions.

or lesser measure during the experiments, increasing the parameter T50% in The pure praseodymium oxide catalyst (Pr100) was mixed oxide with the same amount not deactivated. This formulation, so

These conclusions were corroborated by the analysis of fresh and used catalysts by Raman spectroscopy (Figures 5a and b, respectively).

Most of the fresh catalysts (Figure 5a) show in the Raman spectrum the characteristic band of the cerite fluorite structure around 465. This band moves progressively by incorporating Pr to the mixed oxide, which is evidence that It is incorporating praseodymium into the crystal structure of the ceria. The Raman spectra of the catalysts with between 50 and 100% (Ce50Pr50, Ce80Pr50 and Ce100) obtained after the catalytic tests (Figure 5b) continue to show the fluorite characteristic band. However, catalysts with high praseodymium content (Pr100 and Ce20Pr80) undergo a phase transformation, as was also observed by DRX, which is evidenced in its spectrum

LnOCI type compound (Ln being a lanthanide), which usually show tetragonal structure.

the different catalytic tests were also characterized by XPS, and the degree of chlorination is shown in Figure 6

The degree of surface chlorination depended on the composition of the oxide. The

much praseodymium (Pr100 and Ce20Pr80) underwent the highest degrees of chlorination, reaching surface atomic ratios CI / (Ce + Pr) around 1. This value was consistent with the formation of PrOCI, confirming the

achieved by DRX and Raman spectroscopy. On the contrary, cerium-rich samples (Ce100, Ce80Pr20 and Ce50Pr50) suffered less, reaching a minimum for the sample that showed the best catalytic behavior (Ce50Pr50). This degree of chlorination suffered by the Ce50Pr50 catalyst after three catalytic cycles between 150 and 500 ° C did not increase further after 120 hours of reaction at 325 ° C.

Comparing the results obtained by XPS with that observed by DRX and Raman spectroscopy, we conclude that the samples rich in cerium only The results confirmed that the prepared catalysts consisting of Ce-Pr mixed oxides had a high activity to accelerate the combustion of chlorinated volatile organic compounds.

The stability of the catalysts during said combustion depended considerably on the composition of the mixed oxide. Some of the prepared oxides, especially those richest in praseodymium, underwent a strong deactivation due to chemical chlorine poisoning.

Claims (13)

1. Catalytic system for the combustion of volatile organochlorine compounds of the formula: greater than or equal to zero and less than or equal to one, characterized in that the catalyst particle size is between 0.3-0.5

2.

catalytic according to any of the preceding claims characterized in that the mass of the catalyst must be greater than 0.85 g.

3.

Catalytic system according to any of the preceding claims, wherein the organochlorine volatile compound is 1,2-dichloroethane.

Four.

of combustion of volatile organochlorine compounds because it uses a catalytic system according to any of the

5.

Combustion process according to claim 4, wherein the compound

6.

Combustion process according to any of claims 4-5, is carried out at a temperature between 250

7.

Use of a catalyst according to any of claims 1-3 for the control of emissions of volatile organochlorine compounds.

8.

Use of a catalyst according to any of claims 1-3 for the treatment of gaseous streams containing 1,2-dichloroethane.

FIG. 1

-

.-Pr100 80 .. · ~ .... Ce20Pr80

~ .. ·. ~ .... Ce50Pr50 ~ e ... :: lt ;: ... Ce80Pr20 'or quot; § ~ Ce100 Q) gt; e 40 OR OR 150 200 250 300 350 400 450 500 FIG. 2 420 400 380 or ~ ::!2. 360 or or L!) F 340 320 Temperature (ºC) .................................................. .................................................. .................................................. ............... : .. Ce80Pr20 - + - Ce1 00 -JI; '- Pr1 00. *. Ce20Pr80 ..; & .. Ce50Pr50 or 2 3 Cycle number FIG. 3 Time h FIG. 4 10 20 30 40 50 60 28 (º)  FIG. 5

-------------------------------------------------- -------------------------------------------------- -------------------------------------------------- ---------------------

~

(to)   ~ - ~ :: ~: 1 quot; O ..- JAl ._.._._..._......__..._...___------ ·, ._......____. to the quot; O j 1'c ;; j and Q) and Intensity / 50  Raman offset (cm1)

-------------------------------------------------- -------------------------------------------------- -------------------------------------------------- ---------------------

~

~  (b) 1 \ one\ ! ¡¡ ¡~  1 \ i \ go 1 \! \, ' 1 \ A quot; quot; / \ quot; 'quot; f \ / '\ `` Or at ), '11, \ ..) \ ...... / \ - .. / \ ... ~ ....,., ._ ......, .__..__ .. ......... / \ ...-................. / \ Pr-¡nn. quot; O ..... 'C;; quot; ')' \ quot; .... / ......, .... · .... ··, · quot; .... C · ~; ~~ ¡: á6 '.. · and Q) ~ '---. ~ ._----. ~ -............- .. /! \ _ .....-- / ......_._ - _..__. ~ and ~ _A _________________ ~ -1 \ _____ ~ quot; _5 ~~!?: 'J -..... Jt ......, .................. ......................... · ~ ... · ~ .................. ........ /: , · '. · ,, quot;' nD, nn . Intensity / 50 "; ......._............. ~: ~~~~ '.: ~: ~~ ..,  o 100 200 300 400 500 600 700  Raman offset (cm-1) FIG. 6 1.0 ........ ....  D ... QQ) + 0.8 OR --0.6 ~ 0.4 0.2 0.0 O 20 40 60 80 100 Pr (%) SPANISH OFFICE OF THE PATENTS AND BRAND Application no .: 201130641 SPAIN Date of submission of the application: 04.20.2011 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: B01J23 / 10 (2006.01) B01D53 / 86 (2006.01) RELEVANT DOCUMENTS

Category

56 Documents cited Claims Affected

X

MENG -FEI LUO et al. quot; Structure and redox properties of CexPr1-xO2-and mixed oxides and their catalytic activities for CO, CH3OH and CH4 combustionquot; Journal of Molecular Catalysis A: Chemical 2006 Vol. 260 pages 157-162; sections 1-2. 1.2

X

US 2010329954 A1 (YOKOTA et al.) 30.12.2010, examples 1.6, paragraphs [0052-0054]. one

TO

QUINQIN HUANG, XIAOMIN XUE, RENXIAN ZHOU. quot; Decomposition of 1,2-dichloroethane over CeO2 modified USY zeolite catalysts: Effect of acidity and redox property on the catalytic behaviorquot; Journal of Hazardous Materials 14.08.2010 [online] Vol. 183 pages 694-700; sections 1-2. 1-10

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims □ for claims no:

Date of realization of the report 09.03.2012

Examiner V. Balmaseda Valencia Page 1/4

REPORT OF THE STATE OF THE TECHNIQUE Application number: 201130641 Minimum documentation sought (classification system followed by classification symbols) B01J, B01D Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC, WPI, XPESP, NPL, HCAPLUS State of the Art Report Page 2/4 WRITTEN OPINION Application number: 201130641 Date of Written Opinion: 09.03.2012 Statement

Novelty (Art. 6.1 LP 11/1986)

Claims Claims 3-10 1.2 IF NOT

Inventive activity (Art. 8.1 LP11 / 1986)

Claims Claims 3-10 1.2 IF NOT

The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986). Opinion Base.- This opinion has been made on the basis of the patent application as published. State of the Art Report Page 3/4 WRITTEN OPINION Application number: 201130641 1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

MENG -FEI LUO et al. Journal of Molecular Catalysis A: Chemical Vol. 260 pages 157-162. 2006

D02

US 2010329954 A1 (YOKOTA et al.) 12-30-2010

2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement The object of the present invention is a catalytic system for the combustion of organochlorinated volatile compounds ceriopraseodymium, a process for the combustion of organochlorine volatile compounds based on the use of said catalyst and the use thereof for the control of emissions of organochlorinated volatile compounds. Document D01 studies the structure and catalytic properties of a mixed cerium-praseodymium oxide (CexPr1xO2-y) in different proportions (x = 0, 0.2, 0.3, 0.5, 0.7, 0.8, 0.9, 0.95, 0.97, 0.99 and 1.0) and their respective catalytic activities in the combustion of volatile organic compounds (CO, CH3O and CH4) (paragraphs 1.2). Document D03 describes a catalytic system based on cerium oxide and praseodymium oxide in a weight ratio of 90/10 oxide respectively. Said catalytic system is especially suitable for the catalysis of oxidation reactions and / or reduction of organic compounds as well as the treatment of waste gases (paragraphs [0054] - [0056], examples 1.6). Thus, the technical characteristics of claims 1,2 are known from documents D01 and D02. Consequently, it is considered that the object of these claims lacks novelty and inventive activity (Articles 6.1 and 8.1 of the L.P.) The difference between the object of claims 3-10 and documents D01-D02 is that none of said documents discloses a procedure for the combustion of volatile organochlorine compounds (1,2 dichloroethane) with a cerium-praseodymium catalyst with a particle size between 0.3-5mm, in an amount greater than 85g and in a temperature range 250ºC-500ºC. In addition, it would not be obvious to a person skilled in the art said procedure from the cited documents. Accordingly, the object of claims 3-10 is considered to be new and implies inventive activity in accordance Articles 6.1 and 8.1 of the L.P. The attention of the applicant is drawn to the fact that the technical characteristics set forth in claims 3-4 are refer more to the conditions of use of the catalyst in the combustion process of organic compounds organochlorines than the catalyst itself, so it is suggested the inclusion of said characteristics in the claims procedural. State of the Art Report Page 4/4