Titanium dioxide-based fibrous solid

Abstract

This invention comprises 75-95% by weight of titanium dioxide (TiO2) and 1-20% by weight (including the upper limit) of a fibrous mineral compound, based on the total weight of the anhydrous solid, and has an SBET specific surface area of ​​100 m². 2 This invention relates to solids exceeding / g. The fibers contain 70-100% by weight of silica, have an average diameter of 5 nm to 50 μm, and an average length of 50 nm to 1000 μm. The present invention also relates to a method for producing the solid, and in particular to the use of the solid as a carrier or catalyst in a hydrolysis method for sulfur-containing compounds or nitrogen-containing compounds.

Description

[Technical Field]

[0001] This invention relates to titanium dioxide-based solids useful as catalysts or as supports for the preparation of heterogeneous catalysts, and to methods for converting H2S to sulfur, particularly their use in the modified Krauss process. In this method, large amounts of COS and CS2 may be formed, and the use of a catalyst active for their hydrolysis to H2S is necessary, in that case, to ensure a sufficient sulfur yield and to ensure compliance with standards controlling the emission of sulfur compounds into the atmosphere. Titanium dioxide-based catalysts are among the catalysts conventionally used for these hydrolysis processes due to their extremely potent performance.

[0002] These solids can be used in the hydrolysis of COS and HCN in methods for purifying synthesis gas from natural gas, petroleum, coal, or biomass, but they are also useful for the selective reduction of nitrogen oxides to nitrogen in the treatment of fumes from the combustion of nitrogen derivatives, such as during the production of nitric acid.

[0003] The present invention also relates to the preparation of fibrous solids based on titanium dioxide. [Background technology]

[0004] Existing catalysts exhibit average performance, require long residence times, and thus convert sulfur compounds, such as COS or CS2, thus requiring large reactors to limit atmospheric emissions. Improvements in catalyst performance often involve the addition of elements, which increases the price of the catalyst, or a reduction in dimensions such as the catalyst diameter, but the resulting pressure drop becomes sharply larger. Increasing the porosity of the catalyst also improves catalyst performance, but the mechanical strength becomes too low, especially when the catalyst drop height is large, making it impossible to fill industrial units.

[0005] Prior art document Patent Document 1 describes a titanium dioxide (TiO2) based solid, which is prepared by mixing TiO2 powder to form a paste, then molding it, and finally heat-treating it in air at 200-900°C. During the preparation of the solid, molding additives (up to 30% by weight) can be added during the mixing process, and the molding additives can be selected from silica, alumina, clay, silicates, titanium sulfate, and ceramic fibers. It is further disclosed that cellulose, carboxymethylcellulose, carboxyethylcellulose, tall oil, xanthan gum, surfactants, flocculants, such as polyacrylamide, carbon black, starch, stearic acid, polyacrylic acid, polyvinyl alcohol, biopolymers, glucose, and polyethylene glycol can also be added as molding additives.

[0006] The publication by Knapp et al. focuses on the synthesis of TiO2-sepiolite-based supports containing 30-95% TiO2, but sepiolite reduces the amount of titanium at the surface, and increasing the titanium content is possible regardless of whether the molding is done in water or in the presence of acid, up to 100m 2 It has been described that this leads to a decrease in BET surface area of ​​less than 1g. These two aspects are shown to be detrimental to catalytic activity (Non-Patent Literature 1). [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] European Patent No. 38741 [Non-patent literature]

[0008] [Non-Patent Document 1] Knapp et al., “Phase distribution in titania-sepiolite catalyst supports prepared by different methods,” J. Mater. Chem., 1997, 7(8), 1641-1645 [Overview of the Initiative] [Means for solving the problem]

[0009] (Summary of the invention) Surprisingly, the applicant observed that by using a mixture of titanium dioxide at a content of 75-95% with 70-100% silica and 1-20% fibrous mineral binder containing fibers with a median diameter of 5-50 μm and an average length of 50-1000 μm, it was possible to obtain a solid material with superior open porosity compared to known solids while maintaining optimal mechanical strength, and that this material could be used as a catalyst, particularly as a catalyst in the Krauss process, or as a heterogeneous catalyst support.

[0010] Unless otherwise specified, weight percentages are expressed on an anhydrous basis, i.e., based on the weight of the material without water.

[0011] This invention relates to an SBET specific surface area of ​​100 m². 2 More than / g, preferably 120m 2 Solids greater than / g, and the following: - 75-95% by weight of titanium dioxide (TiO2), including the limit, relative to the total weight of the anhydrous solid; - Inorganic compounds in the form of fibers, including limiting values, at a concentration of 1-20% by weight relative to the total weight of the anhydrous solid. Includes, The fiber relates to a solid containing 70-100% by weight of silica, having a median diameter of 5 nm to 50 μm and an average length of 50 nm to 1000 μm.

[0012] The solid according to the invention may contain 80 to 90% by weight of titanium dioxide TiO₂, including the limit value, relative to the total weight of the anhydrous solid.

[0013] The solid according to the invention may contain 2 to 10% by weight of an inorganic compound in fibrous form, including the limit value, relative to the total weight of the anhydrous solid.

[0014] The solid according to the invention contains pores having a diameter of 3.7 nm to 10 μm measured according to ASTM D4284 - 12 standard, and the total pore volume thereof may be more than 0.35 mL / g, preferably more than 0.5 mL / g.

[0015] The inorganic compound may be selected from glass fiber and sepiolite.

[0016] Preferably, the inorganic compound is sepiolite.

[0017] The single pellet crush strength (SPC) of the solid according to the invention may be 1 daN / mm or more, and the crushing rate occurring after impact on a steel plate may be less than 15% by volume.

[0018] The present invention also relates to a method for preparing a solid according to any one of the described variations, which method includes the following steps: i) Mixing a titanium dioxide source containing 90 to 100% by weight of titanium dioxide TiO₂, an inorganic compound in fibrous form, an organic thickening compound, and water in the proportions required to obtain the above - mentioned solid in the presence of a base or an acid; giving a paste ii) Shaping the kneaded paste obtained in step i), preferably by extrusion or granulation; iii) Drying the paste shaped in step ii) at a temperature of 100 to 200 °C; giving a dried product; iv) Firing the dried product at a temperature of 300 to 600 °C.

[0019] The thickening compound may be selected from polysaccharide compounds such as starch, cellulose, carboxymethylcellulose, carboxyethylcellulose, agar, etc., or from polysaccharide compounds obtained by bacterial or fungal fermentation, such as xanthan gum, succinoglycan gum, scleroglucan gum, or heteropolysaccharide S-194.

[0020] The titanium dioxide source may be introduced in a content of 50 to 65% by weight relative to the total mass of the mixture in step i), the inorganic compound in fibrous form may be introduced in a content of 1 to 8% by weight, and the thickening compound may be introduced in a content of 0.5 to 2% by weight.

[0021] The present invention relates to a method for hydrolysis of a sulfur or nitrogen compound contained in a gaseous feed, preferably selected from H2S, COS, CS2 and / or HCN, wherein the gaseous feed is brought into contact with water and a solid prepared by any one of the described modifications or by any one of the preparation methods described.

[0022] The gaseous feed may be the gaseous effluent from the Krauss H2S treatment process.

[0023] The gaseous feed may be synthesis gas.

[0024] Finally, the present invention relates to the use of a solid prepared by any one of the described modifications, or a solid prepared by any one of the described modification methods, as a catalyst or as a heterogeneous catalyst support. [Modes for carrying out the invention]

[0025] (List of drawings) Figures 1 and 2 illustrate the present invention in a non-limiting manner.

[0026] Figure 1 shows a scanning electron microscope image of the catalyst according to Example 1, which contains 90% titanium dioxide and 10% sepiolite clay in the form of very fine fibers (10 nm in diameter, 300 nm in average length).

[0027] Figure 2 shows a scanning electron microscope image of the catalyst according to Example 5, which contains 85% titanium dioxide and 5% glass fibers (14 μm in diameter and 200 μm in length).

[0028] (Description of the embodiment) (term) Throughout this document, groups of chemical elements are described according to the new IUPAC classification. For example, Group 9 or Group 10 corresponds to the metals in columns 9 and 10 of the IUPAC classification, or the last two columns of Group VIIIB of the CAS classification (CRC Handbook of Chemistry and Physics, CRC editor press, Editor-in-Chief DR. Lide, 81st edition, 2000-2001). Similarly, Group 6 corresponds to the metals in column 6 of the IUPAC classification, or the metals of Group VIB of the CAS classification.

[0029] Throughout this document, the total pore volume (TPV) is obtained by mercury intrusion porosimetry according to method ASTM D4284-12 and is expressed as the pore volume generated by pores with diameters of 37 Å to 10 μm.

[0030] SBET specific surface area is the surface area measured by the BET method, i.e., the specific surface area determined by nitrogen adsorption according to the standard ASTM D 3663-78, which was established from the Brunauer-Emmett-Teller method described in The Journal of the American Chemical Society, 6Q, 309 (1938).

[0031] Space-time velocity (SHV) is the volumetric flow rate (m³) of the feed material at the reactor inlet at 0°C and 1 atm. 3The volume of catalyst contained in the reactor (m³) is calculated as follows: 3 It means the ratio obtained by dividing by ).

[0032] The median diameter of inorganic fibers, particularly glass or sepiolite fibers, can be obtained by measuring the diameters of at least 10 fibers observed with a scanning electron microscope. The average length can also be obtained by measuring the lengths of at least 10 fibers observed with a scanning electron microscope.

[0033] The single pellet crush strength (SPC) value is obtained through a standardized test (ASTM standard D4179-01), which involves subjecting a millimeter-sized object, such as a carrier in extruded form in the case of the present invention, to a compressive force that causes it to break. This test is used to indirectly measure the strength of the material. The analysis is repeated for a specific number of individually sampled particles, typically 50 to 200, preferably 100 to 200 particles. The average of the measured lateral crushing forces constitutes the average SPC, which is expressed in units of force (N) in the case of spheroidal particles.

[0034] The fracture rate resulting from impact is obtained using specialized equipment that butts extruded materials against a steel plate. One liter of millimeter-sized extruded material is fed into a tube having a diameter of 30 mm and a length of 50 mm, and subjected to 3 bar of compressed air, which butts each extruded material against a plate located 220 mm from the tube outlet. The sample is then collected, and the dimensions of the obtained material are characterized by laser diffraction. The fracture rate resulting from impact is then expressed as the volume fraction of the extruded material that has been fractured by impact against the steel plate (whose diameter is smaller than that of the original extruded material).

[0035] Unless otherwise specified, weight percentages (weight%) correspond to mass percentages expressed relative to the total mass of the components of the formulation or final solid.

[0036] (Detailed description of the invention) The present invention relates to a solid material comprising 75-95% by weight of titanium dioxide relative to the total weight of anhydrous material and 1-20% by weight of an inorganic compound relative to the total weight of anhydrous material, wherein the inorganic compound preferably contains 70-100% silica, and the inorganic compound is in the form of fibers. The fibers are advantageously in the form of needles having a median diameter of 5 nm to 50 μm and an average length of 50 nm to 1000 μm. The total pore volume of the solid according to the present invention is advantageously greater than 0.35 mL / g (ASTM D 4284-12, volume of pores with a diameter of 3.7 nm to 10 μm). The BET specific surface area of ​​the solid (measured according to standard ASTM D3663-78) is at least 100 m 2 / g, preferably a minimum of 120m 2 It is / g.

[0037] Titanium dioxide used in the manufacture of solids is preferably crystallized (anatase or rutile structure). The term "poorly crystallized" is understood to mean titanium dioxide having an X-ray spectrum that shows a halo instead of the main lines of well-crystallized titanium dioxide. Amorphous is understood to mean titanium dioxide whose X-ray spectrum does not have any diffraction lines.

[0038] According to the present invention, the inorganic compound may be advantageously selected from glass fibers, sepiolite, rock fibers, and asbestos fibers. Preferably, the inorganic compound is sepiolite or glass fibers.

[0039] In a method for producing catalysts or supports, primarily composed of titanium dioxide and involving the use of organic thickening additives, the addition of an inorganic binder in fibrous form unexpectedly and significantly improves the catalytic performance of the product. This increase is possible because the resulting product has a large pore volume and does not adversely affect its mechanical resistance to breakage by crushing or impact.

[0040] (Preparation method) The catalyst can be produced from a titanium dioxide source mixed with an inorganic binder containing 70-100% silica, preferably in the form of fibers, preferably needles. The production method particularly involves forming a paste by kneading the titanium dioxide source, the inorganic binder in the form of fibers to which an acidic or basic solution has been added, and a thickening organic compound type additive, such as xanthan gum. The solid is formed by any technique known to those skilled in the art, and then dried and calcined to form a carrier. Preferably, the solid is formed by extrusion or granulation.

[0041] Advantageously, a method for preparing a carrier according to the present invention may include the following steps: - Step i); Prepare a paste from a mixture containing water, 50-65 wt% titanium dioxide source containing 90-100 wt% TiO2, 1-8 wt% inorganic compound in fibrous form, preferably sepiolite clay or glass fiber, and 0.5-2 wt% organic thickening compound, such as xanthan gum, in the presence of a suitable acid (HCl, HNO3, H2SO4, organic acid (such as acetic acid, citric acid, or maleic acid)) or base (KOH, NaOH, Ca(OH)2, Mg(OH)2, tetraethylammonium hydroxide); - Step ii); Form the paste; for example, by extrusion or granulation of the paste; - Step iii); Dry at 100-200°C, preferably for 1-24 hours; - Step iv); Ceramic at 300°C to 600°C, preferably for 1 to 24 hours, preferably in air, and possibly in a humid state.

[0042] The paste may be prepared in either an acidic or basic medium; preferably, the pH of the suspension in step i) is less than 3 or greater than 11.

[0043] The organic thickening compound is preferably a polysaccharide compound, such as starch, cellulose, carboxymethylcellulose, carboxyethylcellulose, or agar, obtained by bacterial or fungal fermentation. Examples of polysaccharide compounds obtained by bacterial fermentation and suitable for the present invention include xanthan gum, succinoglycan gum, or particularly heteropolysaccharide S-194 described in Japanese Patent EP 77680.

[0044] Xanthan gum is derived from microorganisms, more specifically, bacteria belonging to the genus Xanthomonas, such as those listed in Bergey's Manual of Identification of Bacteriology (8th edition - 1974 - Williams & Wilkins Co., Baltimore) (Xanthomonas begoniae, Xanthomonas campestris, Xanthomonas carotae, Xanthomonas hederae, Xanthomonas incanae, Xanthomonas malvacearum, Xanthomonas papavericola, Xanthomonas phaseoli). It is obtained by fermentation of carbohydrates under the action of Xanthomonas phaseoli, Xanthomonas pisi, Xanthomonas vasculorum, Xanthomonas vesicatoria, Xanthomonas vitians, and Xanthomonas pelargonii.Other microorganisms capable of producing polysaccharides include bacteria belonging to the genus Arthrobacter, more specifically, the species Arthrobacter stabilis, Arthrobacter viscosus; the genus Erwinia; the genus Azotobacter, more specifically, the species Azotobacter indicus; the genus Agrobacterium, more specifically, the species Agrobacterium radiobacter, Agrobacterium rhizogenes, Agrobacterium tumefaciens.

[0045] Suitable polysaccharide compounds obtained by fungal fermentation include scleroglucan gum synthesized by fermentation of carbohydrates using fungi belonging to the genus Sclerotium, more specifically, the species Sclerotium glucanicum and Sclerotium rolfsii.

[0046] The catalyst or support according to the present invention may advantageously be provided in all normal known forms: materials of powders, beads, extrudates and crushed materials. Beads and extrudates are preferred. The size of the beads is advantageously 0.5 to 10 mm, preferably 0.7 to 8 mm. The extrudates may be cylindrical or multilobal, solid or hollow; their size is advantageously 0.5 to 6 mm, preferably 2 to 5 mm.

[0047] The total pore volume (ASTM D 4284-12) of the product thus obtained is more than 0.35 mL / g, preferably more than 0.5 mL / g, and the BET specific surface area (ASTM D 3663-78) is more than 100 m 2 / g, preferably more than 120 m 2More than / g, very preferably 120-150m 2 The catalytic activity is 50% better than that of the conventional technology, and the resistance to crushing by impact is at least equivalent to that of the conventional technology.

[0048] In addition to the components described above, the final solid may contain impurities that can be introduced by the preparation method, particularly by the titanium dioxide source, such as aluminum oxides or sulfates, iron oxides or sulfates, niobium oxides or sulfates, and other impurities selected from aluminum, ferric, ferrous, or niobium impurities.

[0049] The loss on ignition (LOI) of the final solid, expressed as a weight percentage relative to the total weight of the solid, is favorably between 0.5 and 5 weight percent.

[0050] (applicable) The solid according to the present invention is advantageously used as a catalyst for the hydrolysis of COS and CS2 contained in gases treated by the Krauss process, and generally has the composition shown in Table 1 below.

[0051] [Table 1]

[0052] In the case of hydrolysis of COS and HCN for the purification of synthesis gas, such as synthesis gas obtained by biomass gasification or pyrolysis, the composition is typically as shown in Table 2 below.

[0053] [Table 2]

[0054] The pressure during the hydrolysis of COS, CS2, and HCN compounds by solid according to the present invention is generally 0.1 to 5 MPa, preferably 0.5 to 3 MPa, and the temperature is 100 to 400°C, preferably 150 to 250°C, with HSV (0°C, 1 atm) and volumetric flow rate of feed at the reactor inlet (m³). 3 ( / h) Volume of catalyst contained in the reactor (m³) 3 The ratio of ) is 1000~8000h -1 Preferably 500-8000h -1 , preferably 1000-6000h -1 Hydrolysis is carried out in the presence of water, and its content is generally 5-50% by volume relative to the volume of gas to be treated.

[0055] (Advantages of the invention) The solid according to the present invention has superior open porosity and retained resistance to fracture by impact against metal plates compared to the prior art. In fact, the solid according to the present invention has superior catalytic activity compared to the prior art for the conversion of sulfur or nitrogen compounds, such as CS2, COS, and HCN.

[0056] (Examples) (Example A (Comparative Example)) Comparative Example A is a catalyst containing 90% by weight of TiO2 in the form of anatase. This catalyst is prepared by preparing a paste in a Z-arm mixer from water, nitric acid, and anatase powder, for example, G2 from Tronox, the anatase powder containing 10% by weight of calcium sulfate and 90% by weight of TiO2 on a dry basis. The paste thus obtained contains 8% by weight of nitric acid, in which case the loss on ignition is 43.5%.

[0057] The paste is extruded through a die with a cylindrical hole having a diameter of 4 mm. The extruded material is then dried in an oven at 140°C for 2 hours and baked at 450°C for 2 hours in humid air containing 40 g of water per kg of dry air.

[0058] This catalyst has been conventionally used in the first converter of the Krauss process, and it hydrolyzes CS2 and COS to H2S, and sometimes also hydrolyzes HCN.

[0059] (Example 1 (Conforms to the present invention)) The titanium dioxide catalyst is prepared in a Z-arm mixer by preparing a paste from water, nitric acid, xanthan gum, sepiolite clay, and commercially available anatase powder M211 from Venator, the anatase powder M211 containing at least 98% by weight of TiO2 on a dry basis. The paste is obtained by mixing the powder and the acidification solution in the following proportions: - 0.88% by weight xanthan gum - 2.76% by weight of nitric acid - 52.23% by weight of anatase powder M211 - 6.32% by weight sepiolite clay - Residual water.

[0060] The loss on ignition of the paste is 48.5% in this case. Loss on ignition (LOI) is measured as the weight loss corresponding to the following ratio: LOI(%)=(Wo-Wi) / Wo, Wo = initial weight of raw materials Wi = Weight of the raw material after firing at 1000°C for 2 hours in an anhydrous enclosure and cooling to ambient temperature.

[0061] The amount of sepiolite clay is targeted to yield 10% by weight relative to the weight of the final product. The sepiolite clay is in the form of very fine needle-like fibers with a median diameter of approximately 10 nm and an average length of approximately 300 nm.

[0062] The paste is extruded through a die with a cylindrical hole having a diameter of 4 mm. The extruded material is then dried in an oven at 140°C for 2 hours, and then baked at 450°C for 2 hours in humid air containing 40 g of water per kg of dry air.

[0063] (Example 2 (Conforms to the present invention)) The titanium dioxide catalyst is prepared in a Z-arm mixer by preparing a paste from water, nitric acid, xanthan gum, sepiolite clay (fibers with a median diameter of 10 nm and an average length of approximately 300 nm), and anatase powder G2 from Tronox, the anatase powder G2 containing 10% by weight of calcium sulfate and 90% by weight of TiO2 on a dry basis. The paste is obtained by mixing the powder and the acidification solution in the following proportions: - 0.94% by weight xanthan gum - 3.15% by weight of nitric acid - 56.31% by weight of anatase powder G2 - 6.50% by weight sepiolite clay - Residual water.

[0064] The amount of sepiolite clay is targeted to yield 10% by weight relative to the weight of the final product. The loss on ignition of the paste is 46.8%.

[0065] The paste is extruded through a die with a cylindrical hole having a diameter of 4 mm. The extruded material is then dried in an oven at 140°C for 2 hours and baked at 450°C for 2 hours in humid air containing 40 g of water per kg of dry air.

[0066] (Example 3 (Conforms to the present invention)) The titanium dioxide catalyst is prepared in a Z-arm mixer by preparing a paste from water, nitric acid, xanthan gum, needle-shaped glass fibers having a median diameter of 14 μm and an average length of 200 μm, and commercially available anatase powder G2 from Tronox. The paste is obtained by mixing an aqueous solution containing the following, relative to the weight of the mixture: - 0.93% by weight xanthan gum - 3.29% by weight of nitric acid - 58.50% by weight of anatase powder G2 - 3.20% by weight of glass fiber - Residual water.

[0067] The amount of glass fiber is targeted to yield 5% by weight relative to the weight of the final product. The loss on ignition of the paste is 47.7%.

[0068] The paste is extruded through a die with a cylindrical hole having a diameter of 4 mm. The extruded material is then dried in an oven at 140°C for 2 hours and baked at 450°C for 2 hours in humid air containing 40 g of water per kg of dry air.

[0069] (Example 4 (Conforms to the present invention)) The titanium dioxide catalyst is prepared in a Z-arm mixer by preparing a paste from water, nitric acid, xanthan gum, sepiolite clay in the form of needles with a median diameter of 10 nm and an average length of approximately 300 μm, and anatase powder G2 from Tronox.

[0070] The paste is obtained by mixing an aqueous solution containing the following, relative to the weight of the mixture: - 0.92% by weight xanthan gum - 3.38% by weight of nitric acid - 60.0% by weight of anatase powder G2 - 1.60% by weight sepiolite clay - Residual water.

[0071] The amount of sepiolite clay is targeted to yield 2.5% by weight relative to the weight of the final product. In this case, the loss on ignition of the paste is 47.7%.

[0072] The paste is extruded through a die having a cylindrical hole with a diameter of 4 mm. The extruded material is then dried in an oven at 140°C for 2 hours, and then baked at 450°C for 2 hours in humid air containing 40 g of water per kg of dry air.

[0073] (Example 5 (Conforms to the present invention)) The titanium dioxide catalyst is prepared in a Z-arm mixer by preparing a paste from water, nitric acid, xanthan gum, agar, needle-shaped glass fibers (median diameter 14 μm and average length 200 μm), and anatase powder G2 from Tronox.

[0074] The paste is obtained by mixing an aqueous solution containing the following, relative to the weight of the mixture: - 0.92% by weight of agar - 3.26% by weight of nitric acid - 58.0% by weight of anatase powder G2 - 3.17% by weight of glass fiber - Residual water.

[0075] The amount of glass fiber is targeted to obtain 5% by weight relative to the weight of the final product. In this case, the loss on ignition of the paste is 48.2%.

[0076] The paste is extruded through a die with a cylindrical hole having a diameter of 4 mm. The extruded material is then dried in an oven at 140°C for 2 hours and baked at 450°C for 2 hours in humid air containing 40 g of water per kg of dry air.

[0077] The properties of the obtained extruded catalysts are compared with those shown in Table 3 below.

[0078] [Table 3]

[0079] The open porosity (particularly the total pore volume TPV) of the catalyst of the present invention, as measured by mercury injection, is therefore significantly superior to that of conventional catalyst A, while maintaining sufficient mechanical strength, with SPC ≥ 1 daN / mm, and the fragmentation rate after impact is less than 15% by volume.

[0080] (Example 6) This example illustrates the application of the catalyst of the present invention for the conversion of CS2 by hydrolysis under conditions simulating the first converter of the Kraus process. This reaction is considered a model for evaluating the performance of catalysts under these conditions, as its reaction rate is much slower than that of COS hydrolysis.

[0081] [ka]

[0082] The following gas mixture is sent to a reactor maintained at 320°C: - 3% by volume H2S - 2% SO2 by volume - 1000ppmv CS2 - 30% by volume H2O - Remaining volume (up to 100% by volume) N2.

[0083] The reactor contains 30 g of the catalyst according to the present invention. The total gas flow rate is set to 4000 and 6000 h in relation to the volume of catalyst in the reactor. -1 The HSV is adjusted to reach a certain value. The HSV in this embodiment is deliberately chosen to be significantly better than the HSV of the industrial Krauss process in order to highlight the activity of the catalyst that converts CS2.

[0084] The CS2 conversion reported during the use of the obtained extrusion catalyst is compared with Table 4 below.

[0085] [Table 4]

[0086] Therefore, thanks to its much higher open porosity, the catalyst of the present invention is expected to achieve a CS2 conversion rate under conditions simulating the first converter of the Krauss process that is far higher than the conversion rates observed with conventional catalysts, such as the catalyst of Comparative Example A. [Brief explanation of the drawing]

[0087] [Figure 1] The image shown is a scanning electron microscope image of the catalyst according to Example 1, which contains 90% titanium dioxide and 10% sepiolite clay in the form of very fine fibers (diameter 10 nm, average length 300 nm). [Figure 2] The image shown is a scanning electron microscope image of the catalyst according to Example 5, which contains 85% titanium dioxide and 5% glass fibers (14 μm in diameter, 200 μm in length).

Claims

1. SBET specific surface area is 100 m ２ A solid that is greater than / g, and the following: - 75-95% by weight of titanium dioxide (TiO2) relative to the total weight of the anhydrous solid, including the limit value. ２ ; - Inorganic compounds in the form of fibers, including limit values, at a concentration of 1 to 20% by weight relative to the total weight of the anhydrous solid. Includes, The fiber is a solid containing 70 to 100% by weight of silica, with a median diameter of 5 nm to 50 μm and an average length of 50 nm to 1000 μm.

2. 80-90% by weight of titanium dioxide (TiO2), including the limit, relative to the total weight of the anhydrous solid. ２ The solid according to claim 1, comprising:

3. The solid according to claim 1 or 2, comprising 2 to 10% by weight of an inorganic compound in fibrous form, including a limiting value, relative to the total weight of the anhydrous solid.

4. The solid according to any one of claims 1 to 3, comprising pores whose diameter is measured according to the ASTM D4284-12 standard and is 3.7 nm to 10 μm, wherein the total pore volume is greater than 0.35 mL / g, preferably greater than 0.5 mL / g.

5. The inorganic compound is selected from glass fiber and sepiolite, the solid according to any one of claims 1 to 4.

6. The solid according to claim 5, wherein the inorganic compound is sepiolite.

7. The solid according to any one of claims 1 to 6, wherein the single pellet crushing strength (SPC) is 1 daN / mm or more, and the crushing rate that occurs after impact to the steel plate is less than 15% by volume.

8. A method for preparing a solid according to any one of claims 1 to 7, comprising the following steps: i) 90-100% by weight of titanium dioxide (TiO) ２ A process of mixing a titanium dioxide source containing a fibrous inorganic compound, an organic thickening compound, and water in the presence of a base or acid; to give a paste; ii) A step of molding the kneaded paste obtained in step i); preferably by extrusion molding or granulation; iii) A step of drying the paste formed in step ii) at a temperature of 100-200°C; giving a dried product; iv) A process of calcining the dried product at a temperature of 300-600°C.

9. A method for preparing a solid according to claim 8, wherein the thickening compound is selected from polysaccharide compounds such as starch, cellulose, carboxymethylcellulose, carboxyethylcellulose, agar, etc., or polysaccharide compounds obtained by bacterial or fungal fermentation, such as xanthan gum, succinoglycan gum, scleroglucan gum, or heteropolysaccharide S-194.

10. A method for preparing a solid according to claim 8 or 9, comprising introducing a titanium dioxide source at a content of 50 to 65% by weight relative to the total mass of the mixture in step i), introducing an inorganic compound in fibrous form at a content of 1 to 8% by weight, and introducing a thickening compound at a content of 0.5 to 2% by weight.

11. It is contained in the gaseous feed, preferably H ２ S, COS, CS ２ A method for hydrolysis of a sulfur or nitrogen compound selected from and / or HCN, comprising contacting the gaseous feed with water and a solid prepared according to any one of claims 1 to 7, or any one of claims 8 to 10.

12. The gaseous material is Krauss H ２ The hydrolysis method according to claim 11, wherein the gaseous effluent is obtained from the S treatment method.

13. The hydrolysis method according to claim 11, wherein the gaseous feed is synthesis gas.

14. Use of a solid according to any one of claims 1 to 7, or a solid prepared according to any one of claims 8 to 10, as a catalyst or as a heterogeneous catalyst support.

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