CA2969445A1

CA2969445A1 - Catalyst, preparing method and use thereof, and sulfur recovering method

Info

Publication number: CA2969445A1
Application number: CA2969445A
Authority: CA
Inventors: Cuicui Xu; Jirong Wu; Jiandong ZHANG; Jianli Liu; Aihua Liu; Weidong Tao; Zengrang Liu
Original assignee: China Petroleum and Chemical Corp
Current assignee: China Petroleum and Chemical Corp
Priority date: 2016-06-07
Filing date: 2017-06-01
Publication date: 2017-12-07
Anticipated expiration: 2037-06-01
Also published as: NL2019020A; NL2019020B1; RU2670606C1; RU2670606C9; CN107469803B; CN107469803A; CA2969445C

Abstract

The present invention relates to a catalyst, preparing method and use thereof, and sulfur recovering method using the catalyst. The catalyst comprises a titanium dioxide carrier, lutetium oxide and/or cerium oxide, and calcium oxide, wherein based on 100% weight of the catalyst, the content of the titanium dioxide is 80-96 wt%, the content of calcium oxide is 2-10 wt%, and the content of lutetium oxide and/or cerium oxide is 2-10 wt%. The catalyst of the present invention takes lutetium and/or cerium as active ingredients, titanium dioxide as a carrier, and calcium as an alkaline regulator, with specific contents for cooperation, when used in the sulfur recovery process, it has better activity stability, better organo-sulfur hydrolysis activity and Claus activity, with organo-sulfur hydrolysis activity>=99%, and Claus activity>=80%. The catalyst provided in the present invention has easy preparing process, and the preparing procedure has no secondary pollution.

Description

CATALYST, PREPARING METHOD AND USE THEREOF, AND SULFUR
RECOVERING METHOD
Field of the Invention The present invention relates to a catalyst, preparing method and use thereof, and sulfur recovering method using the catalyst.
Background of the Invention The main function of the sulfur recovery process is to process the hydrogen sulfide generated during the processing procedure of such as petroleum, natural gas and coal-coking and thus to recover sulfur resources. At present, as the laws and rules of environmental protection become stricter and stricter worldwide, the quality of the crude oil continuously worsens, and the natural gas and coal chemical industries develop rapidly, the importance of the sulfur recovery process has been increasingly emerging.
Regarding the sulfur recovery catalyst, as one of the key factors influencing the operation effect of a sulfur recovery device, the operation effect thereof directly relates to the sulfur recovery rate of the entire sulfur recovery device, and finally influences the discharge of sulfur dioxide in the flue gas from the device. In April 2015, China issued Emission Standard of Pollutants for Petroleum Refining Industry, which regulates: the limited value of the discharging concentration of the sulfur dioxide from the sulfur recovery device is 400mg/m3, specific area executes a specific limited value of 100mg/m3, which will be executed by the existing companies from 1 July 2017, and by the newly founded companies from 1 July 2015. Such standard is the strictest discharging standard in the world so far. Therefore, a higher requirement on the performance of the sulfur recovery catalyst is required.
An excellent sulfur recovery catalyst must have good activity stability, and higher organo-sulfur hydrolysis activity and Claus activity. In addition, as the natural gas and coal chemical industry rise, the properties of the raw materials for the sulfur device become more complex, which also requires the sulfur recovery catalyst to have good activity stability and organo-sulfur hydrolysis activity.
The sulfur recovery catalyst substantially underwent three developing phases:
a natural bauxite catalyst phase, an active aluminum oxide catalyst phase and a phase of mutual development of various catalysts. Earlier industrial devices use a natural bauxite catalyst, the sulfur recovery rate is only 80-85%, various sulfide not converted is burned and then discharged into the atmosphere in the form of SO2, which seriously pollute the environment. Later, the aluminum oxide based sulfur recover catalyst is developed, and the total sulfur recovery rate is remarkably increased. The sulfur recovery catalysts currently used on the industrial devices mainly are the active aluminum oxide catalyst, titaniferous aluminum oxide catalyst and Ti-based catalyst. Each sulfur recovery catalyst has its own advantages and disadvantages. The most wildly used active aluminum oxide based catalyst has good activity in the initial period, has a certain extent organo-sulfur hydrolysis activity, but the activity is reduced rapidly as the using time increases, which is mainly caused by catalyst sulfated poisoning. The titaniferous aluminum oxide based catalyst has improved organo-sulfur hydrolysis activity, but it still has the disadvantage of easily being sulfated poisoned.
For example, CN100503034C discloses a titanium dioxide loading method when preparing a catalyst, and a bifunctional sulfur recovery catalyst prepared by the method. The catalyst, based on the weight ratio relates to: TiO2 is 5-30%, MgO is 3-7%, and r-A1203 is 63-92%. It overcomes the hydrogen chloride pollution and corrosion generated by the prior titanium tetrachloride loading method. However, the main body of the catalyst carrier thereof is still aluminum oxide, and it has the disadvantage of being easily sulfated.
The Ti-based sulfur recovery catalyst has received increasing attention due to its outstanding organo-sulfur hydrolysis performance. The titanium precursor of the Ti-based sulfur recovery catalyst generally is the metatitanic acid generated by sulfuric acid method, which generally contains 3-8 wt% of sulfate radical. In order to further improve the organo-sulfur hydrolysis performance and activity stability of the Ti-based sulfur recovery catalyst, those skilled in the art still conduct a large amount of researches.
For example, CN103111305B discloses a catalyst for a Claus sulfur recovery process, characterized in that the catalyst carrier, according to the weight components, zirconium oxide 20-30, titanium oxide 20-30, and silicon oxide 30-50, are mixed and pressed into a ball shaped or a block shaped initial blank. Then an additive, based on the weight components, two or more of zinc oxide 10-30, manganese oxide 10-35, chromic oxide 1-5, and iron oxide 1-3, are pulped. The catalyst carrier is poured into the pulp, and the additive thereof has a proportion of 10-35% in the catalyst carrier. It is calcined in a furnace at 700-1100 C for 1-2 hours and then cooled. Palladium or platinum is added to 40% ammonium nitrate solution to prepare a solution with a concentration of 0.5-3.0mol/L. Nickel is added to 30% the ammonium nitrate solution to prepare a solution with a concentration of 1.0-4.0mol/L. The aforementioned two solutions are mixed to obtain a mixed liquid. The calcined catalyst carrier containing the additive is poured into the mixed liquid for immersion, and after dried in the air, the catalyst is obtained. The preparing process of the catalyst is complex and the cost for the catalyst is high.

2 Summary of the Invention The purpose of the present invention is to provide a novel catalyst and preparing method thereof.
When applied to the sulfur recovery process, the catalyst has better activity stability, and better organo-sulfur hydrolysis activity and Claus activity, and can improve the sulfur recovery rate of the sulfur recovery device, and reduce discharging of sulfur dioxide in the flue gas from the sulfur recovery device. Preparation of the catalyst is easy to be carried out.
The inventor of the present invention found that, when the catalyst obtained through using titanium dioxide as a carrier, together with calcium oxide alkaline regulator, and lutetium oxide and/or cerium oxide active components at specific contents is used for sulfur recovery process, the activity stability, organo-sulfur hydrolysis activity and Claus activity of the catalyst are obviously increased.
Moreover, preparation of the catalyst is easy to be carried out.
A first aspect of the present invention provides a catalyst, comprising a titanium dioxide as carrier, lutetium oxide and/or cerium oxide, and calcium oxide, wherein based on 100%
weight of the catalyst, the content of the titanium dioxide is 80-96 wt%, the content of calcium oxide is 2-10 wt%, and the content of lutetium oxide and/or cerium oxide is 2-10 wt%.
A second aspect of the present invention provides a method for preparing a catalyst, comprising:
extrusion moulding, drying and calcining a titanium precursor, a calcium precursor, soluble salt of lutetium and/or cerium, an extrusion aid and a binder after homogeneous mixing; wherein the amounts of titanium precursor, the calcium precursor, and the soluble salt of lutetium and/or cerium are enabled so that based on 100% weight of the obtained catalyst, the content of titanium dioxide is 80-96 wt%, preferably 85-95 wt%, the content of calcium oxide is 2-10 wt%, preferably 2-8 wt%, more preferably 2-5 wt%, and the content of lutetium oxide and/or cerium oxide is 2-10 wt%, preferably 2-8 wt%, more preferably 2-5 wt%.
A third aspect of the present invention further provides a use of the aforementioned catalyst in sulfur recovery.
A fourth aspect of the present invention further provides a method for recovering sulfur, comprising:
under Claus reaction conditions and in the presence of the aforementioned catalyst, contacting acid gas and oxygen-containing gas, to obtain sulfur and Claus tail gas.
The catalyst of the present invention, taking lutetium and/or cerium as active ingredients, titanium dioxide as a carrier, and calcium oxide as an alkaline regulator, with specific contents for cooperation, when used in the sulfur recovery process, has better activity stability, better organo-sulfur hydrolysis activity and Claus activity, with organo-sulfur hydrolysis activity>99%, and Claus activity>80%.

3 The method for preparing the catalyst provided in the present invention obtains the catalyst through kneading, extruding, drying and calcining the metatitanic acid, calcium precursor, soluble salt of lutetium and/or cerium, extrusion aid and binder after homogeneous mixing. As compared with an impregnation method, the kneading extruding method may ensure the upper amount of the active ingredient and the physical stability of the catalyst. According to a preferred embodiment of the present invention, taking the metatitanic acid prepared by using a chlorination method as the titanium precursor can further improve the organo-sulfur hydrolysis activity and Claus activity of the catalyst and further improve the activity stability of the catalyst. The inventor of the present invention found that, regarding the existing Ti-based sulfur recovery catalyst, since the sulfate radical is attached on the catalyst, the catalyst would be sulfated easily, thereby influencing the catalyst activity; on the other hand, a large amount of sulfate radicals of the sulfur recovery catalyst will remarkably influence the activity stability thereof.
The catalyst provided in the present invention can be easily prepared, and the preparing procedure has no secondary pollution. Using the catalyst can remarkably improve the sulfur recovery rate of the device, facilitate reducing the discharge of sulfur dioxide in the flue gas from the sulfur recovery device, and have remarkable economic benefits and social benefits with the environmental protection standards being gradually stricter and stricter.
Brief Description of Drawings The accompanying drawings are provided here to facilitate further understanding on the present invention, and constitute a part of this document. They are used in conjunction with the following embodiments to explain the present invention, but shall not be comprehended as constituting any limitation to the present invention. Among the figures:
FIG. 1 is a flow chart of preparing the catalyst provide by the present invention.
FIG. 2 is a flow chart of an evaluation device for catalyst activity.
Detailed Description of the Embodiments Hereunder some embodiments of the present invention will be detailed. It should be appreciated that the embodiments described here are only provided to describe and explain the present invention, but shall not be deemed as constituting any limitation to the present invention.
Limits of scope or any value revealed herein are not limited this specific scope or value, but rather these scope or value should be considered as values including those close to such scope or value. For

4 numeric ranges, the end points of the ranges, the end points of the ranges and the discrete point values, and the discrete point values can be combined to obtain one or more new numeric ranges, which shall be deemed as having been disclosed specifically in this document.
A first aspect of the present invention provides a catalyst, comprising a titanium dioxide as carrier, lutetium oxide and/or cerium oxide, and calcium oxide, wherein based on 100%
weight of the catalyst, the content of the titanium dioxide is 80-96 wt%, the content of calcium oxide is 2-10 wt%, and the content of lutetium oxide and/or cerium oxide is 2-10 wt%.
In the catalyst provided in the present invention, alkaline earth calcium may increase the number of basic sites of the catalyst which facilitates the reaction of the organo-sulfur hydrolysis.
Based on 100% weight of the catalyst, the content of calcium oxide is 2-8 wt%, preferably 2-5 wt%.
According to an embodiment of the present invention, based on 100% weight of the catalyst, the content of titanium dioxide is 85-95 wt%, the content of calcium oxide is 2-8 wt%, preferably 2-5 wt%, and the content of lutetium oxide and/or cerium oxide is 2-8 wt%, preferably 2-5 wt%.
In the present invention, the content of lutetium oxide and/or cerium oxide means (1) the total content of lutetium oxide and cerium oxide when both present; (2) the content of lutetium oxide when cerium oxide not present; (3) the content of cerium oxide when lutetium oxide not present.
According to a preferred embodiment of the present invention, the catalyst further contains promoter.
Based on 100% weight of the catalyst, the content of titanium dioxide is 85-95%, the content of calcium oxide is 2-5%, preferably 2.5-4%, the content of lutetium oxide and/or cerium oxide is 2-5%, preferably 2-4%, and the content of the promoter is 0-5%, preferably 1-

5%, more preferably 2-4%.
In the present invention, the metal content in the catalyst is measured by using an X ray fluorescence spectrometry (XRF) method, which using a ZSX-100e type X ray fluorescence spectrograph, using an Rh target, and measuring under the condition of a current of 50 mA, and a voltage of 50 kV.
In the present invention, the titanium dioxide preferably is anatase type titanium dioxide. As compared with rutile type titanium dioxide, using anatase type titanium dioxide as a carrier can ensure the catalyst to have higher organo-sulfur hydrolysis activity, Claus activity, and activity stability, and the mechanical strength of the catalyst is higher.
In the present invention, the promoter is used to improve the specific surface area and pore volume of the catalyst to increase the Claus activity of the catalyst. The promoter, for example, can be one or more of Y-typed molecular sieve, silicon dioxide, and aluminum oxide.
According to a preferred embodiment of the present invention, the content of the sulfate ions in the catalyst is less than 1000 ppm, preferably free from sulfate ions.

The metatitanic acid through the chlorination method can be used as a carrier precursor to obtain the aforementioned lower sulfate ions content.
The present invention further provides a method for preparing a catalyst, comprising: kneading, extruding, drying and calcining titanium precursor, calcium precursor, soluble salt of lutetium and/or cerium, extrusion aid and binder after homogeneous mixing, wherein the amounts of the metatitanic acid, calcium precursor, soluble salt of lutetium and/or cerium are enabled, so that based on 100%
weight of the obtained catalyst, the content of titanium dioxide is 80-96 wt%, preferably 85-95 wt%, the content of calcium oxide is 2-10 wt%, preferably 2-8 wt%, more preferably 2-5 wt%, and the content of lutetium oxide and/or cerium oxide is 2-10 wt%, preferably 2-8 wt%, more preferably 2-5 wt%.
According to the present invention, the aforementioned titanium precursor may be various substances that can obtain the titanium dioxide after calcining, such as metatitanic acid.
Preferably, the metatitanic acid is made from the chlorination method, and is free from sulfate radical. Further preferably the specific surface of the metatitanic acid is not less than 210 m2/g, and the pore volume is not less than 0.25 ml/g. Further preferably the specific surface of the metatitanic acid is not less than 220 m2/g, for example 220-260 m2/g, and the pore volume is not less than 0.28m1/g, for example, 0.28-0.35m1/g. Further preferably the specific surface is not less than 230 m2/g, and the pore volume is not less than 0.30 ml/g. Larger specific surface area and pore volume facilitate the catalyst to have a higher Claus activity. The metatitanic acid meeting the aforementioned conditions, for example, may be purchased from Shanghai Yifu Industry Co., Ltd.
The catalyst of the present invention is prepared using the extrusion moulding method. As compared with the impregnation method, the catalyst obtained using the extruding method has higher mechanical strength, more even active ingredients, and larger specific surface area and pore volume, so that the catalyst has higher organo-sulfur hydrolysis activity, Claus activity and activity stability and a long service life.
The calcium precursor may be one or more of Ca(NO3)2, CaCO3, and calcium oxalate.
The soluble lutetium salt is preferably one or more of lutetium carbonate, lutetium nitrate, and lutetium acetate.
The soluble cerium salt may be one or more of cerium carbonate, cerium nitrate, and cerium acetate.
The binder is one of acetic acid, nitric acid, citric acid, soluble glass, and silica sol, preferably citric acid. Based on 100% weight of the catalyst, an adding amount of the binder may be 1-5%, preferably 2.5-3.5%.
The extrusion aid may be one or more of sesbania gum, polyvinyl alcohol, Y-typed molecular sieve,

6 starch, and citric acid, preferably sesbania gum.
Preferably, the use amounts of the extrusion aid and binder are 1-5% of the weight of the titanium precursor, respectively.
The amounts of the extrusion aid and binder after calcining correspond to the amount of the promoter in the aforementioned catalyst.
The drying temperature may be 100-150 C, preferably 120-130 C; and the drying time may be 4-12 hours, preferably 6-10 hours.
The calcining temperature may be 340-500 C, preferably 390-460 C; and the calcining time may be 3-8 hours, preferably 4-6 hours. Under the aforementioned calcining condition, the anatase type titanium dioxide can be obtained.
According to a preferred embodiment of the present invention, as shown in FIG.
1, the method for preparing the catalyst of the present invention includes the following steps:
(1) selecting metatitanic acid prepared through the chlorination method as a raw material for preparing a carrier of the catalyst;
(2) according to the proportion of the catalyst weight, respectively weighing and taking soluble salt(s) of lutetium and/or cerate, calcium salt, binder and extrusion aid;
dissolving soluble components using deionized water; evenly stirring to prepare a solution A; and fully and homogeneously mixing insoluble components and the metatitanic acid, to obtain a solid material;
(3) pouring the solution A into the solid material, and fully mixing;
(4) placing the mixed materials into an extruding machine for fully kneading, until the materials are homogeneously mixed;
(5) extruding the materials after kneading in the extruding machine to obtain a catalyst strip;
(6) drying the catalyst strip;

(7) calcining the dried catalyst strip to prepare the catalyst.
The amount of water is based on ensuring the soluble components and subsequent kneading and extruding steps to be smoothly carried out. Generally, it is 0.3-0.7 fold of the weight of the titanium precursor.
The standard of the catalyst strip may be selected according to requirements.
For the sulfur recovery process, the standard of the catalyst strip preferably is (1)4x3-10mm.
The present invention further provides a catalyst obtained using the aforementioned method and a use thereof in the sulfur recovery. Based on 100% weight of the obtained catalyst, the content of titanium dioxide is 80-96 wt%, preferably 85-95 wt%, the content of calcium oxide is 2-10 wt%, preferably 2-8 wt%, more preferably 2-5 wt%, and the content of lutetium oxide and/or cerium oxide is 2-10 wt%, preferably 2-8 wt%, more preferably 2-5 wt%.
The catalyst provided in the present invention is free from sulfate radical, has strong sulfation resistance, good activity stability, and good organo-sulfur hydrolysis activity and Claus activity.
According to a preferred embodiment of the present invention, the catalyst prepared in the present invention is free from sulfate radical, the specific surface is greater than 200m2/g, the pore volume is greater than 0.25 ml/g, the outer shape is a long strip, and the standard is (4x3-10mm. The catalyst has organo-sulfur hydrolysis activity>99%, and Claus activity>80%.
The catalyst provided in the present invention can be used to process acid gas generated in industries such as petroleum refining, natural gas purification, and coal chemical industry, to increase the sulfur recovery rate of the sulfur recovery device. The acid gas generally contains ingredients such as hydrogen sulfide, carbon dioxide, traces of light hydrocarbons, ammonia, and water, which is well known to those skilled in the art.
The present invention further provides a method for recovering sulfur, comprising: under Claus reaction conditions and in the presence of a catalyst, contacting acid gas and oxygen-containing gas, to obtain sulfur and Claus tail gas. The catalyst contains a titanium dioxide as carrier, rare-earth oxide, and alkaline earth oxide. Based on 100% weight of the catalyst, the content of the titanium dioxide is 80-96 wt%, the content of the alkaline earth oxide is 2-10 wt%, and the content of the rare-earth oxide is 2-10 wt%.
The rare-earth oxide is preferably one or more of lanthanum oxide, lutetium oxide and cerium oxide, more preferably lutetium oxide and/or cerium oxide.
The alkaline earth oxide is preferably one or more of barium oxide, calcium oxide and magnesium oxide, more preferably calcium oxide and/or magnesium oxide, in particular, preferably calcium oxide.
According to a preferred embodiment of the present invention, the catalyst is the catalyst provided by the first aspect of the present invention. That is, the catalyst contains titanium dioxide carrier, lutetium oxide and/or cerium oxide, and calcium oxide. Based on 100% weight of the catalyst, the content of the titanium dioxide is 80-96 wt%, the content of calcium oxide is 2-10 wt%, and the content of lutetium oxide and/or cerium oxide is 2-10 wt%.
Preferably, in the acid gas, the content of hydrogen sulfide is 45-95 volume%.
The Claus reaction refers to a chemical reaction of enabling the hydrogen sulfide to be incompletely combusted, and then enabling the generated sulfur dioxide and hydrogen sulfide to be subjected to the reverse disproportionation reaction for generating sulfur and water. The Claus reaction conditions are conventional options in the art. The present invention has no particular requirements. For

8 example, it may be the Claus reaction condition recited in the documents (Gengliang CHEN, et al, Claus Method in Sulfur Recovery Process Technique, Petroleum Industry Press, 2007).
Typically, the Claus reaction conditions include: during the stage in which the hydrogen sulfide is incompletely combusted, the temperature is 1000-1400 C, preferably 1100-1350 C, the pressure is 0.010-0.040 MPa, preferably 0.020-0.030 MPa, and the retention time is 2-8 seconds, preferably 3-6 seconds.
During the stage in which the reverse disproportionation reaction occurs to sulfur dioxide and hydrogen sulfide, the temperature is 200-350 C, preferably 220-250 C, the pressure is 0.001-0.020 MPa, preferably 0.002-0.003 MPa, and the gaseous hourly space velocity is 600-1200 hours-1.
In the present invention, pressure means gage pressure.
The materials obtained through the reverse disproportionation reaction can be cooled to 130-150 C, and then are subjected to gas-liquid separation to obtain liquid sulfur and remaining gas (the Claus tail gas).
The remaining gas can be further contacted with the catalyst under the Claus reaction conditions for the next stage of Claus reaction, thereby improving the conversion rate for converting hydrogen sulfide in the acid gas to sulfur. That is, multiple stages Claus reactions can be carried out. Generally, 2-4 stages Claus reaction, preferably 2 stages Claus reaction can be carried out. The conditions of the multiple stage Claus reactions can be the same or different as long as the Claus reaction can occur.
The following embodiments will further explain the present invention.
In the following examples, the constitution of the catalyst is measured by using the X ray fluorescence spectrometry (XRF) method. The X ray fluorescence spectrometry (XRF) method includes using a ZSX-100e type X ray fluorescence spectrograph, using an Rh target, and measuring under the condition of a current of 50 mA, and a voltage of 50 kV.
The pore volume and specific surface area of the catalyst and the carrier are measured using a low-temperature nitrogen adsorption method (see Petroleum and Chemical Analysis Method (RIPP
experimental method)), edited by Cuiding YANG et al, Science Press, published in 1990).
The lateral pressure strength of the catalyst is measured using HG/T2783-1996.
The titanium dioxide in the catalyst is detected whether to be the anatase type titanium dioxide by X
Ray Diffraction (XRD) method. The results are that the Examples 1-23 are all anatase type titanium dioxide.
The Si02 content in the silica sol used in the examples is 25 wt%, and is manufactured by Qingdao Ocean Chemical Industry Co., Ltd. The Y-typed molecular sieve is the NaY
molecular sieve manufactured by Zibo Xinhong Chemical Trade Co., Ltd.

9 Example I
Weigh and take 2304g of metatitanic acid prepared by the chlorination method (purchased from Shanghai Yifu Industrial Co., Ltd., the following is the same), as a raw material for preparing the catalyst carrier. Respectively weigh and take 71g of lutetium nitrate, 76g of cerium nitrate, and 175g of calcium nitrate. Weigh and take 60g of citric acid as a binder, 60g of sesbania gum as an extrusion aid. Add a proper amount of deionized water (50g of deionized water every 100g of metatitanic acid) into lutetium nitrate, cerium nitrate, calcium nitrate, and citric acid for dissolving; evenly stir to prepare a solution A. Homogeneously mix the sesbania gum and metatitanic acid.
Slowly pour the solution A into the mixed solid material, and fully mix. Then place the resulted material after mixed into an extruding machine for fully kneading, until the material is homogeneously mixed. Place the material after kneading into the extruding machine for extruding, to obtain a long strip with the standard of (b4x3-10mm. Dry the long strip of (1)4x3-10mm under the temperature of 125 C for 8 hours. Calcine the dried long strip of 41)4x3-10mm under the temperature of 400 C for 5 hours to obtain a catalyst a. The constitution and physical and chemical properties of the catalyst are shown in TABLE 2.
Examples 2-20 Prepare the catalyst according to the method in Example 1, except that types and ratio of the materials and the drying and calcining conditions are shown in TABLE 1 as follows to respectively obtain a catalyst b to catalyst t. The constitution and physical and chemical properties of the catalyst are shown in TABLE 2.
Example 21 Prepare the catalyst according to the method in Example 1, except that the metatitanic acid prepared by the chlorination method is replaced by the metatitanic acid prepared by the sulfuric acid method (the content of sulfate ions is 3 wt%) with the same weight to obtain a catalyst u. The constitution and physical and chemical properties of the catalyst are shown in TABLE 2.
Comparative examples 1-3 Prepare the catalyst according to the method in Exampe 1, except that types and ratio of the materials and the drying and calcining conditions are shown in TABLE 1 as follows to respectively obtain catalysts DI-D3.

Example 22 Using an isovolumetric impregnation method to prepare a catalyst, the constitution of the catalyst is the same as that of Example 1, and the detail operations are as follows:
Weigh and take 1880g of titanium dioxide powder (purchased from Jinan Yuxing Chemical Industry Co., Ltd., free from sulfate radical, being the anatase type) for extrusion moulding and calcining, and then obtain a long strip of (1)4x3-10mm as a catalyst carrier. Weigh and take 71g of lutetium nitrate, 76g of cerium nitrate, and 175g of calcium nitrate, respectively. Add a proper amount of deionized water (30g deionized water for 100g of the catalyst carrier) into lutetium nitrate, cerium nitrate, calcium nitrate, and citric acid for dissolving, and evenly stir, to prepare a solution A. Use the isovolumetric impregnation method to immerse the titanium dioxide carrier in the solution A, and then dry at the temperature of 125 C for 8 hours. Calcine the dried substance at the temperature of 400 C for 5 hours, to prepare a catalyst v. The constitution and physical and chemical properties of the catalyst are shown in TABLE 2.
Example 23 Prepare the catalyst according to the method in Example 22, except that titanium dioxide is replaced by the metatitanic acid of the same weight based on the titanium dioxide to prepare a catalyst w. The constitution and physical and chemical properties of the catalyst are shown in TABLE 2.
Example 24 Prepare the catalyst according to the method in Example 22, except that the anatase type titanium dioxide is replaced by the rutile type titanium dioxide of the same weight, to prepare a catalyst x. The constitution and physical and chemical properties of the catalyst are shown in TABLE 2.

Alkaline Dry Calcine Ex. Carrier raw Active ingredient regulator Bind Extrusio No. material raw material raw er n aid Temper Time TemperTime material ature ature lutetium cerium calcium citric metatitanic sesbania Ex. 1 n itrate nitrate nitrate acid 125V 8h 400 V 5h acid 2304g gum 60g 71g 76g 175g 60g lutetium cerium calcium citric metatitanic sesbania Ex. 2 nitrate nitrate nitrate acid 125 C 8h 400 C 5h acid 2353g gum 25g 47g 50g 117g 40g lutetium cerium calcium citric sesbania metatitanic Ex. 3 nitrate nitrate nitrate acid gum 125 C 8h 400 C 5h acid 2206g 118g 126g 293g 80g 100g lutetium cerium calcium citric metatitanic sesbania Ex. 4 nitrate nitrate nitrate acid 125 C 8h 400 C 5h acid 2084g 189g 151g 468g 70g gum 50g metatitanic lutetium cerium calcium citric sesbania Ex. 5 nitrate nitrate nitrate acid 125 C 8h 400 C 5h acid 2157g 189g 202g 234g 50g gum 80g lutetium cerium calcium citric metatitanicsesbania Ex. 6 nitrate nitrate nitrate acid 125 C 8h 400 C 5h acid 1961g 236g 252g 585g 60g gum 70g lutetium calcium citric metatitanicsesbania Ex. 7 nitrate / nitrate acid 125 C 8h 400 C 5h acid 2280g 165g 205g 60g gum 60g cerium calcium citric metatitanic sesbania Ex. 8 / nitrate nitrate acid 125 C 8h 400 C 5h acid 2255g gum 40g 177g 263g 50g lutetium cerium calcium citric sesbania metatitanic Ex. 9 nitrate nitrate nitrate acid gum 125 C 8h 400 C 5h acid 2206g 47g 151g 351g 100g 100g lutetium cerium calcium citric metatitanicsesbania Ex. 10 nitrate nitrate nitrate acid 125 C 8h 400 C 5h acid 2304g71g gum 60g 76g 175g 60g lutetium cerium calcium citric metatitanicsesbania Ex. 11 nitrate nitrate nitrate acid 125 C 8h 400V 5h acid 2353g 47g 50g 117g 40g gum 25g lutetium cerium calcium citric sesbania metatitanic Ex. 12 nitrate nitrate nitrate acid gum 125 C 8h 400 C 5h acid 2206g 118g 126g 293g 80g 100g lutetium cerium calcium citric metatitanic.sesbania Ex. 13 ntrate nitrate nitrate acid 125 C 8h 400 C 5h acid 2084g 189g 151g , 468g 70g gum 50g lutetium cerium calcium citric metatitanicsesbania Ex. 14 nitrate nitrate nitrate acid 125 C 8h 400 C 5h acid 2157g gum 80g 189g 202g 234g 50g lutetium cerium calcium citric metatitanicsesbania Ex. 15 nitrate nitrate nitrate acid 125 C 8h 400 C 5h acid 1961g 236g 252g 585g 60g gum 70g lutetium calcium citric metatitanic sesbania Ex. 16 nitrate / nitrate acid 125 C 8h 400 C 5h acid 2280g gum 60g 165g 205g 60g cerium calcium citric metatitanic sesbania Ex. 17 / nitrate nitrate acid 125 C 8h 400 C 5h acid 2255g gum 40g 177g 263g , 50g lutetium cerium calcium citric sesbania metatitanic Ex. 18 nitrate nitrate nitrate acid gum 125 C 8h 400 C 5h acid 2206g 47g 151g 351g , 100g 100g aceti Y-typed lutetium cerium calcium - .
metatitanic c molecul Ex. 19 acetate acetate carbonat 150 C 4h 340 C 8h acid 2280g 90g 90g e 100g acid ar sieve 25g 20g_ acetic lutetium silica metatitanic acid citric Ex. 20 nitrate / sol140 C 6h 360 C 6h acid 2280g 100g calcium 400g acid 20g 110g , metatitanic acid same (sulfuric same as same as same as same as same as same as same as same Ex. 21 as acid Ex. 1 Ex. 1 Ex. 1 Ex. 1 Ex. 1 Ex. 1 Ex. 1 as Ex. 1 method)230 Ex. 1 4g metatitanic acid calcium citric CEx. (sulfuric sesbania / / nitrate acid 125 C 8h 400 C 5h 1 acid gum 80g 175g 60g method)230 4g acetic acid same as same same CEx. same as same as same as same as same as lanthan / Example as as 2 Example I Ex. 1 Ex. 1 Ex. 1 Ex. 1 urn 1 Ex. 1 Ex. 1 150g magnesi same as same as same same CEx. same as um same as same as same as same as Exampl Exampl as as 3 Example 1 nitrate Ex. 1 Ex. 1 Ex. 1 Ex. 1 e 1 e 1 Ex. 1 Ex. 1 175g Lateral Pore Specific Active Alkaline Promot Catalyst volume surface pressure Carrier Example No. ingredient regulator er /mL=g-1 No. strength area, m2/g /N=cmi i .f (wt%) (wt%) (wt%) (wt%) Example 1 a 0.35 225 161 94 3 3 /
Example 2 b 0.33 222 153 96 2 2 /
Example 3 c 0.33 231 159 90 5 5 /
Example 4 d 0.32 226 158 85 7 8 /
Example 5 e 0.31 223 156 88 8 4 /
Example 6 f 0.28 218 157 80 10 10 /
Example 7 g 0.28 217 158 93 3.5 3.5 /
Example 8 h 0.3 220 156 92 3.5 4.5 /
Example 9 i 0.32 230 163 90 4 6 /
Example 10 j 0.33 224 160 93.3 3.6 3.1 /
Example 11 k 0.32 223 155 95.4 2.5 2.1 /
, Example 12 1 0.3 222 156 88.6 6.2 5.2 /
Example 13 m 0.31 221 157 91.6 4.8 3.6 /
Example 14 n 0.32 225 156 91.1 4.8 4.1 /
Example 15 o 0.32 224 156 91.3 6.1 2.6 /
Example 16 p 0.29 220 163 92.3 4.1 3.6 /
i Example 17 q 0.32 225 159 91.1 4.4 4.6 /
Example 18 r 0.33 222 158 94.1 3.8 2.1 /
Example 19 s 0.35 228 165 91 5 3 1 Example 20 t 0.32 222 159 90 3 2 5 Example 21 u 0.31 226 160 91 3 3 /
CEx. 1 Dl 0.3 225 159 93 / 3.6 /
CEx. 2 D2 0.28 202 150 92.8 3.8 3.4 /
CEx. 3 D3 0.27 205 156 94.6 3 2.4 /
Example 22 v 0.24 185 135 94 3 3 /
Example 23 w 0.25 188 140 94 3 3 /
Example 24 x 0.23 182 142 94 3 3 /
It can be seen from the data in Table 2 that, the catalyst prepared according to the preferred embodiment of the present invention has higher specific surface area, pore volume and mechanical strength.
Performance Test The evaluation test of the activity of the sulfur recovery catalyst is carried out on a 10m1 sulfur micro reactor device, the reactor is made of a stainless steel tube with an inner diameter of 20mm, the reactor is placed in a thermostat container, and the detail process procedure is shown in FIG. 2. Send hydrogen, oxygen, hydrogen sulfide, sulfur dioxide, nitrogen and carbon disulfide in a required proportion by a mass flow meter MFC into a buffer tank. Then the above kinds of gas were sent together with water into the reactor for the Claus reaction. The sulfur collector collects sulfur. The out gas is sent to a cold trap for cooling, and then enters an alkaline cleaning system for alkaline cleaning. The tail gas is unloaded. The filling amount of the catalyst is 10m1, and quartz sands with the same granularity are filled in an upper part for mixing and preheating.
The contents of H2S, SO2, COS, and CS2 in gas at the entrance and exit of the reactor are analyzed on line using the Shimadu GC-2014 gas chromatograph, the sulfide is analyzed by using the GDX-301 supporter, the 02 content is analyzed by using the 5A molecular sieve, the column temperature is 120 C
, a thermal conductivity detector is used, hydrogen is used as carrier gas, and post-column velocity is 25m1/min.
Take 2H2S + SO2¨> ¨3 Sx+2H20 as an index reaction, observe the Claus activity of the catalyst, the x volume constitution of the entrance gas is H2S 2%, SO2 1%, 02 3000 ppm, and H20 30%, and the remaining is N2. The gaseous hourly space velocity is 2500h-1, the reaction temperature is 230 C, and the Claus Conversion Rate of the catalyst is calculated according to the following formula:
Mo ¨ MI
11h2s+so2¨ ____________________________________ M x100%o Wherein: Mo represents the sum of the volume concentrations of H2S and SO2 at the entrance and M1 represents the sum of the volume concentrations of H2S and SO2 at the exit.
Sample and analyze once every hour, and the analyzed result is an average value of 10 hours.
Take CS2+2H20¨*CO2 2H2S as an index reaction, observe the organo-sulfur hydrolysis activity of the catalyst, the volume constitution of entrance gas is H2S 2%, CS2 0.6%, SO2 1%, 02 3000 ppm, and H20 30%, and the remaining is N2, the gaseous hourly space velocity is 2500h* the reaction temperature is 280 C, and the CS2 hydrolysis rate of the catalyst is calculated according to the following formula:
CO¨Cl rIcs2= ______________________________________ x100%
Co Wherein: Co and C1 are respectively volume concentrations of CS2 at the entrance and the exit.
Sample and analyze once every hour, and the analyzed result is an average value of 10 hours.
The activity of the fresh catalyst after reacting for 5 hours and the activity of the catalyst after strict aging, which indicate the activity stability of the catalyst, are evaluated by using the aforementioned method.
The evaluation process for the sulfur recovery catalyst activity normally always is carried out for 10 hours. For a fresh catalyst, 10 hours of continuous operation has no great influence on the using performance of the catalyst. In order to observe the influence of the operating time on the using performance of the catalyst, and evaluate the stability of the catalyst, a method of man-made strict aging is generally used to process the catalyst so that in a short period of time, the condition of the catalyst after using for a long period of time can be simulated. Regarding the catalyst aged according to the following strict aging test, the test results are equivalent to the performance conditions of the catalyst after used for 3 years.
The strict aging test: calcine the catalyst at 550 C for 2 hours, then contact with mixed gas of SO2:
air: water vapor=1: 2.5: 6.5(volume ratio) at the temperature of 260 C for 2 hours, and the gaseous hourly space velocity is 1000h*
The activities of the catalysts prepared according to the aforementioned method in the aforementioned examples and comparative examples are evaluated, and the results are shown in the following TABLE 3.

Example Claus activity, % Organo-sulfur hydrolysis activity, No. Catalyst After strict aging After strict React for 5 hours React for 5 hours aging Example 1 a 81.6 66.9 99.6 90.8 Example 2 b 81.5 66.7 99.5 90.6 Example 3 c 81.5 66.8 99.4 90.7 Example 4 d 81.4 66.5 99.2 90.3 Example 5 e 81.5 66.6 99.4 90.3 Example 6 f 81.2 66.3 99.3 90.2 Example 7 g 81.3 66.4 99.4 90.4 Example 8 h 81.4 66.4 99.2 90.3 Example 9 i 81.5 66.6 99.3 90.3 Example j 81.5 66.8 99.4 90.7 Example k 81.4 66.6 99.2 90.3 Example 1 81.2 66.3 99.4 90.3 Example m 81.5 66.7 99.4 90.4 Example n 81.4 66.5 99.5 90.3 Example o 81.5 66.7 99.4 90.3 Example P 81.3 66.4 99.3 90.2 Example 9 81.5 66.7 99.4 90.3 Example r 81.4 66.6 99.4 90.4 Example s 81.8 67.3 99.7 91.7 Example t 81.5 66.8 99.6 90.6 Example u 80.5 65.1 98.2 88.5 CEx. 1 Dl 76.5 60.2 87.6 76.8 CEx. 2 D2 76.8 60.4 88.5 77.2 CEx. 3 D3 76.7 60.5 88.8 77.0 Example 80.2 63.5 97.9 88.1 Example 80.3 63.8 98.4 88.8 Example 78.2 62.6 92.1 85.3 Note: in above Table 1 to Table 3, Ex. means example, CEx. means comparative example.
It can be seen from the data in Tables 1-3 that, the catalyst prepared by the method of the present invention has higher Claus activity and organo-sulfur hydrolysis activity, and has higher activity stability.
While some preferred embodiments of the present invention are described above, the present invention is not limited to the details in those embodiments. Those skilled in the art can make modifications and variations to the technical scheme of the present invention, without departing from the spirit of the present invention. However, all these modifications and variations shall be deemed as falling into the protected scope of the present invention.
In addition, it should be appreciated that the technical features described in the above embodiments can be combined in any appropriate manner, provided that there is no conflict among the technical features in the combination. To avoid unnecessary iteration, such possible combinations are not described here in the present invention.
Moreover, different embodiments of the present invention can be combined freely as required, as long as the combinations don't deviate from the ideal and spirit of the present invention. However, such combinations shall also be deemed as falling into the scope disclosed in the present invention.

Claims

1. A catalyst, comprising a titanium dioxide as carrier, lutetium oxide and/or cerium oxide, and calcium oxide, wherein based on 100% weight of the catalyst, the content of the titanium dioxide carrier is 80-96 wt%, the content of calcium oxide is 2-10 wt%, and the content of lutetium oxide and/or cerium oxide is 2-10 wt%.

2. The catalyst according to claim 1, wherein based on 100% weight of the catalyst, the content of titanium dioxide is 85-95 wt%, the content of calcium oxide is 2-8 wt%, and the content of lutetium oxide and/or cerium oxide is 2-8 wt%.

3. The catalyst according to claim 1, wherein based on 100% weight of the catalyst, the content of titanium dioxide is 85-95 wt%, the content of calcium oxide is 2-5 wt%, and the content of lutetium oxide and/or cerium oxide is 2-5 wt%.

4. The catalyst according to any one of claims 1-3, wherein an specific surface area of the catalyst is 210-250 m2/g, a pore volume is not less than 0.25 mL/g, and a lateral pressure strength is 140-170 N.cndot.cm-1.

5. The catalyst according to claim 4, wherein an specific surface area of the catalyst is 210-230 m2/g, a pore volume is 0.25-0.4 mL/g, and a lateral pressure strength is 150-165 N.cndot.cm-1.

6. The catalyst according to any one of claims 1-5, wherein the catalyst further contains, based on 100% weight of the catalyst, 0-5% of a promoter.

7. The catalyst according to claim 6, wherein based on 100% weight of the catalyst, the content of titanium dioxide is 85-95%, the content of calcium oxide is 2-5%, the content of lutetium oxide and/or cerium oxide is 2-5%, and the content of the promoter is 1-5%.

8. The catalyst according to claim 6 or 7, wherein, the promoter is one or more of a Y-typed molecular sieve, silicon dioxide, and pseudo-boehmite.

9. The catalyst according to any one of claims 1-8, wherein the content of sulfate ions in the catalyst is less than 1000 ppm.

10. The catalyst according to any one of claims 9, wherein the catalyst is free from sulfate ions.

11. The catalyst according to any one of claims 1-10, wherein the titanium dioxide is an anatase type titanium dioxide.

12. A method for preparing a catalyst, comprising: extrusion moulding, drying and calcining a titanium precursor, a calcium precursor, soluble salt of lutetium and/or cerium, an extrusion aid and a binder after homogeneous mixing; wherein the use amounts of the titanium precursor, the calcium precursor, and the soluble salt of lutetium and/or cerium are enabled so that based on 100% weight of the obtained catalyst, the content of titanium dioxide is 80-96 wt%, the content of calcium oxide is 2-10 wt%, and the content of lutetium oxide and/or cerium oxide is 2-10 wt%.

13. The preparing method according to claim 12, wherein the use amounts of titanium precursor, the calcium precursor, and the soluble salt of lutetium and/or cerium are enabled so that based on 100% weight of the obtained catalyst, the content of titanium dioxide is 85-95 wt%, the content of calcium oxide is 2-8 wt%, and the content of lutetium oxide and/or cerium oxide is 2-8 wt%.

14. The preparing method according to claim 12, wherein the use amounts of titanium precursor, the calcium precursor, and the soluble salt of lutetium and/or cerium are enabled so that based on 100% weight of the obtained catalyst, the content of titanium dioxide is 85-95 wt%, the content of calcium oxide is 2-5 wt%, and the content of lutetium oxide and/or cerium oxide is 2-5 wt%.

15. The preparing method according to any one of claims 12-14, wherein the titanium precursor is metatitanic acid, which is free from sulfate ions, and has following properties: the specific surface area is not less than 210 m2/g, the pore volume is not less than 0.25 mL/g.

16. The preparing method according to claim 15, wherein the metatitanic acid has following properties: the specific surface area is 220-260 m2/g, the pore volume is 0.28-0.35 mL/g.

17. The preparing method according to claim 15 or 16, wherein the metatitanic acid is prepared by a chlorination process.

18. The preparing method according to any one of claims 12-17, wherein each of the amounts of the extrusion aid and the binder is 1-5% of the weight of the titanium precursor; and the extrusion aid is selected from the group consisting of one or more of sesbania gum, polyvinyl alcohol, Y-typed molecular sieve, starch and citric acid; the binder is selected from the group consisting of one or more of acetic acid, nitric acid, citric acid, soluble glass, and silica sol.

19. The preparing method according to any one of claims 12-18, wherein the calcium precursor is one or more of Ca(NO3)2, CaCO3, calcium oxalate; the soluble lutetium salt is one or more of lutetium carbonate, lutetium nitrate, and lutetium acetate; and the soluble cerium salt is one or more of cerium carbonate, cerium nitrate, and cerium acetate.

20. The preparation method according to any one of claims 12-19, wherein the calcining temperature is 340-500°C, and the calcining time is 3-8 hours.

21. The preparation method according to any one of claims 12-20, wherein the drying temperature is 100-150°C and the drying time is 4-12 hours.

22. Use of the catalyst according to any one of claims 1-11 in sulfur recovery.

23. A method for recovering sulfur, comprising: under Claus reaction conditions and in the presence of a catalyst according to any one of claims 1-11, contacting acid gas with oxygen-containing gas, to obtain sulfur and Claus tail gas.

24. The method according to claim 23, wherein in the acid gas, the content of hydrogen sulfide is 45-95 volume%, the Claus reaction conditions include: during the stage in which hydrogen sulfide is incompletely combusted, the temperature is 1000-1400°C, the pressure is 0.010-0.040 MPa, and the retention time is 2-8s; and during the stage when reverse disproportionation reaction occurs to sulfur dioxide and hydrogen sulfide, the temperature is 200-350°C, the pressure is 0.001-0.020 MPa, and the gaseous hourly space velocity is 600-1200 h-1.

25. The method according to claim 24, wherein the Claus reaction conditions include: during the stage in which hydrogen sulfide is incompletely combusted, the temperature is 1100-1350°C, the pressure is 0.020-0.030 MPa, and the retention time is 3-6s; and during the stage when reverse disproportionation reaction occurs to sulfur dioxide and hydrogen sulfide, the temperature is 220-250 °C, the pressure is 0.002-0.003 MPa.