Abstract:
This invention is related to a preparation method of a supported catalyst Mo—O—K-Me x O y  for the synthesis of methanethiol from H 2 S-containing syngas. The catalyst comprises of an active component of Mo—O—K-based species, an active promoter and a support denoted as metal (or metals)-carrier. The support is prepared by electroless plating method in such a way that the metal or metals chosen are plated onto the surface of the carrier. Transition metal, especially Fe, Co or Ni are selected to be the plating metal, while SiO 2 , Al 2 O 3  or TiO 2  are selected to be carrier. The catalyst thus prepared is found to be efficient for the synthesis of methanethiol from H 2 S-containing syngasor carbon oxides/hydrogen mixtures, especially regarding a minor formation of the by-product CO 2 .

Description:
[0001]    The present invention relates to a preparation method of a supported Mo—O—K-Me x O y  catalyst for the synthesis of methanethiol from high H 2 S-containing syngas, therein support is a metal (or metals)-plated carrier, especially metal (or metals)-plated-SiO 2 , which is made by electroless plating method. 
       THE PRIOR ART 
       [0002]    As an important chemical material used to produce methionine, pesticides and medicine, methanethiol is predominantly prepared by the reaction of hydrogen sulfide with methanol. The direct synthesis of methanethiol from the reaction of H 2 S with carbon oxides, in particular, from H 2 S-containing syngas is an attractive alternative. For example, EP167,354 disclosed a synthesis pathway from the reaction of hydrogen sulfide with carbon monoxide in the presence of a catalyst NiO or MoO 3  supported on TiO 2 ; Chinese patent CN98118186.4 and CN98118187.2 disclosed Mo—S—K/SiO 2  catalysts used for methanethiol synthesis from high H 2 S-containing syngas; Chinese patent appl.200310100496.1 and 200310100495 reported Mo—O—K/SiO 2  catalysts promoted by transition metal oxides or rare earth metal oxides for the methanethiol synthesis, herein the promoters were selected from the oxides of Co, Ni, Fe, Mn or the rare earth oxides of La, Ce, the active component Mo—O—K base are formed from the precursor K 2 MoO 4  or (NH 4 ) 6 Mo 7 O 24 .4H 2 O plus potassium salt. Those catalysts were prepared by traditional impregnation method. The catalysts exhibit high selectivity and space-time-yield of methyl mercaptan, but produce also by-products, such as carbonyl sulfide, methane and dimethyl sulfide. 
       STATEMENT OF THE INVENTION 
       [0003]    The object of this invention is to develop a further improved solid supported Mo—O—K-Me x O y  catalyst with high activity and selectivity of methanethiol, but lower selectivity of CO 2 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0004]    The object of the invention is a catalyst comprising:
   a) a support, consisting of a porous carrier and a metal A deposited thereon by electroless deposition of metal on the carrier;   b) a Mo—O—K based active component; and   c) optionally an active promoter Me x O y , chosen from the group of transition metal oxides or rare earth metal oxides or rare earth metal oxides, wherein x and y depend on the valence of the metal.   
 
         [0008]    The catalyst comprises an active component, optionally an active promoter and a support. Said active component is a Mo—O—K-based component. Said promoter is at least one chosen from the group of transition metal oxides, or rare earth metal oxides, comprising especially from the oxides of iron, cobalt, Nickel, manganese, lanthanum and cerium, and expressed as Me x O y , wherein “Me” denotes the metal selected from the group of transition metals of rare earth metals, especially Fe, Co, Ni, Mn, La or Ce. 
         [0009]    Said support is a metal (or metals)-plated carrier, especially metal (or metals)-SiO 2 , which is made by electroless plating method. In general the carrier used is porous and chosen from the group of SiO 2 , Al 2 O 3 , TiO 2 , Zeolites, especially SiO 2 . Said metal or metals plated on said carrier can be selected from the group of Ni, Co or Fe, preferably Ni or Co. 
         [0010]    When potassium molybdate is used as precursor of the Mo—O—K-based component, the catalyst of present invention is denoted as K 2 MoO 4 -Me x O y /Metal-carrier, wherein the weight ratios of the components of the catalyst are 
         [0000]      K 2 MoO 4 /Me x O y /metal-carrier=(1-30)/(0.0-25.0)/(0.1-10.0)-100, preferably (15-20)/(0.0-25.0)/(0.5-8.0)-100; 
         [0000]    when (NH 4 ) 6 Mo 2 O 24 .4H 2 O plus one of potassium salts or MoO 3  plus one of potassium salts serve as precursors of the Mo—O—K-based compound, the catalyst of the present invention is expressed as MoO 3 —K 2 O-Me x O y /metal-carrier, wherein the weight ratios of the components of the catalyst are:
 
MoO 3 /K 2 O/Me x O y /metal-carrier=(1-30)/(1-20)/(0.0-25.0)/(0.1-10.0)-100, preferably (15-20)/(10-15)/(0.0-25.0)/(0.5-8.0)-100; Said potassium compound is at least one chosen from the group, comprising
 
       K 2 CO 3 , KOH, KNO 3  and CH 3 COOK. 
       [0011]    Chemically metal-plating method is used to prepare said metal (or metals)-carrier the metal (or metals) chosen is plated onto the carrier chosen, wherein the weight ratio of metal (or metals)/carrier is (0.1-10.0)/100, preferably (0.5-8.0)/100. 
         [0012]    The invention is also directed to the preparation of said catalysts by multi-step impregnation. 
         [0013]    In order to distribute the active component more equally over the support, at least one chelating reagent should be used in the impregnation process. 
         [0014]    Said chelating or coordinating reagent is at least one chosen from the group comprising citric acid, ammonium citrate, L-glutamic acid, tartaric acid and ethylenediaminetetraacetic acid(EDTA); the amount of chelating agent added correspondingly is 0.1-0.6 times as much by weight as that of the support, more preferably is 0.3-0.6 times as much as that of the support. Suitable amounts of ammonia are added to adjust the pH value of the steeping liquor to 7.0-13.0, preferable 8.0-12.0. 
         [0015]    The activation of the carrier by chemically plating metal proceeds as follows (shown as a preferred method):
   (1) the preparation of metal-plating solution:
       A given quantity of soluble metal salt chosen and a given quantity of coordinating agent are dissolved in a given quantity of distilled water successively to produce a metal-plating solution, in which the concentration of the metal ions varies from 1 g/l to 20 g/l, preferably 5-7 g/l; the coordinating agent is at least one chosen from Na 3 C 6 H S O 7 .2H 2 O, C 6 H 8 O 7 .H 2 O, C 2 H 8 N 2  or NaKC 4 H 4 O 6 .4H 2 O, the concentration of the coordinating agent varies from 1 g/l to 20 g/l.   Keeping stirring for 10 minutes, then a given quantity of the stabilizing agents (NH 4 ) 2 SO 4  or Na 3 C 6 H S O 7 .2H 2 O, is added subsequently to the plating solution obtained above followed by stirring for another 20 minutes, followed by adding some NH 3 .H 2 O to adjust the pH of the plating solution to 7.0-13.0, preferably 8.0-12.0; finally, a suitable amount of distilled water is added to adjust the volume of the solution in such a way that the concentration of metal salt chosen in the plating solution varies from 1 g/l to 20 g/l, preferably 5-7 g/l.   
       (2) Pretreatment of the carrier:
       Prior to plating the metal onto the carrier, the carrier is preferably pretreated by the following processes:   a) the carrier should be washed with distilled water, and then dried, followed by immersing the clean carrier in a solution of 4.5 mol/1H 2 SO 4 +0.88 mol/1H 2 O 2  (1:1) for 5 minutes under agitating, and subsequently washed with distilled water three times;   b) the cleaned carrier is immersed in an aqueous solution of activation agent under agitation, said activation agent is preferably PdCl 2 /HCl, the concentration of the activation agent varies in general from 0.05 g/l to 1.0 g/l, preferably from 0.1 g/l to 0.5 g/l; keeping ultrasonically agitating for e.g. 30-35 minutes, then washing with distilled water three times;   c) the activated carrier is immersed in an aqueous solution of a reducing agent under agitation; the reducing agent is preferably NaH 2 PO 4  or NaBH 4 ; the concentration of the agent varies from 20 g/l to 30 g/l;   
       (3) Plating of metal onto carrier is conducted by putting the pretreated carrier produced in step (2) into the plating solution of the metal chosen at 40-85° C. for 30-40 minutes. The metal-platted carrier is washed with distilled water e.g. for three times and then dried at about 110° C. for about 6 hours. The metal-plated carrier is termed support, such as support Ni—SiO 2  or Co—SiO 2 .
 
Impregnation of the Support with the Active Component (Shown as a Preferred Method)
   
 
         [0025]    (1) A given quantity of said precursor K 2 MoO 4  or (NH 4 ) 6 Mo 7 O 24  plus a potassium salt or MoO 3  plus a soluble potassium compound and suitable amount of chelating agent are dissolved in distilled water to generate an impregnation solution; into which then a suitable amount of NH 3 .H 2 O is dropped to adjust the pH of the impregnation solution at 8-12, preferably 8-10; then the metal-plated carrier (30-45 meshes) produced in step (3) of carrier activation is soaked in the impregnation solution at room temperature for 12 hours, then dried at 120° C. for 5 hours to produce the desired supported Mo—O—K catalyst. 
         [0026]    (2) Alternatively, a given quantity of said precursor K 2 MOo 4  or (NH 4 ) 6 Mo 7 O 24  plus a soluble potassium compound or MoO 3  plus a potassium salt are dissolved in distilled water, then a suitable amount of NH 3 .H 2 O is dropped into the solution to make the precursor fully dissolved in the distilled water to generate an impregnation solution, which contains only an active component. 
         [0027]    In a preferred case a given quantity of soluble transition metal salt or rare earth metal salt chosen, especially, its sulfate, nitrate or acetate, and suitable amount of chelating agent are added to the above described solution, into which a suitable amount of NH 3 .H 2 O is then dropped to adjust the pH of the impregnation solution at 8-12, preferably 8-10; lastly the metal (or metals)-plated carrier (30-45 meshes) produced in step (3) of carrier activation is soaked in the impregnation solution at room temperature for 12 hours, then filtered and dried at 110° C. for 6 hours to produce the desired supported Mo—O—K-Me x O y  catalyst. 
         [0028]    Said catalyst is used for a method to prepare methanethiol from high H 2 S-containing syngas. The reaction conditions are known from the state of art. 
         [0029]    The catalyst should be sulfided for 8-10 h before using. 
         [0030]    The reactivity evaluation of the catalyst of present invention was carried out in a fixed-bed tubular reactor with 0.5 ml of catalyst per pass. The reaction conditions are preferably CO/H 2 /H 2 S=1/1/2, 250-350° C., about 0.05-0.3 MPa and GHSV=500-3000 h −1 . The products were analyzed by GC. All date were taken after the steady state achieved. 
         [0031]    The assay results show that the catalyst of the present invention were not only has high catalytic activity for the synthesis of methanethiol from high H 2 S-containing syngas, but also has high selectivity of methanethiol, but less selectivity of CO 2 . 
         [0032]    The following examples illustrate the present invention further. 
       Example 1 
     Electroless Plating 
       [0033]    (1) 2.0 g of NiSO 4 .7H 2 O and 2.0 g of Na 3 C 6 H S O 7 .2H 2 O were dissolved in 50 ml of distilled water successively to produce a plating solution, keeping stirring for 10 minutes, then 3.0 g of (NH 4 ) 2 SO 4  and 3.0 g of NaH 2 PO 4 .H 2 O were added one after another to the solution obtained above, stirring for another 20 minutes, followed by adding some NH 3 .H 2 O to adjust the pH of the solution to 9.0; finally, distilled water was added to adjust the volume of the solution to 100 ml in such a way that the concentration of NiSO 4  in the plating solution is 20 g/l; 
         [0034]    (2) 10 g of clean SiO 2  was immersed in 20 ml of 4.5 mol/l H 2 SO 4 +0.88 mol/l H 2 O 2 (1:1) solution for 5 minutes under agitating, and then washed for three times with distilled water; followed by immersing the carrier SiO 2  in 20 ml of 0.1 g/l PdCl 2 /HCl solution, keeping ultrasonically agitating for 30 minutes, and then washed for three times with distilled water; the next step was to immerse the activated carrier SiO 2  in 10 ml of 30 g/l NaH 2 PO 4  solution, at the same time agitating for 10 seconds and repeated the reduced experiment step again, so as to form an activated carrier. 
         [0035]    (3) The electroless plating process was carried out by immersing the activated carrier SiO 2  in the plating solution prepared in step (2) at appr. 40° C. for 30 minutes. After plating, the Ni-plated SiO 2  was washed with distilled water three times and dried at 383K for 4 h. The weight ratio of metal over carrier of the support thus prepared was Ni—SiO 2 =4.4-100. 
         [0036]    (4) 0.45 g of K 2 MoO 4  and 3.0 g of tartaric acid were dissolved in 6 ml of distilled water to generate an impregnation solution, into which then 0.8 ml of NH 3 .H 2 O was dropped to adjust the pH of the impregnation solution at 9. Then 3 g of support Ni—SiO 2  (30-45 meshes) produced in step (3) was soaked in the impregnation solution at room temperature for 12 hours, then dried at 110° C. for 5 hours. The weight ratio of every component of the catalyst was K 2 MoO 4 /Ni—SiO 2 =15/(4.4-100). The evaluation result of the catalyst thus prepared is shown in table 1. 
       Example 2, 3, 4 
       [0037]    The catalysts were prepared according to the experiment steps described in Example 1, but the concentration of the plating solution was respectively diluted by once, twice three times with distilled water, namely the nickel ion concentration was respectively 10 g/1, 6.67 g/1, 5 g/l. The weight ratio of every content of the catalysts gained was K 2 MoO 4 /Ni—SiO 2 =15/(2.2-100), K 2 MoO 4 /Ni—SiO 2 =15/(1.5-100), K 2 MoO 4 /Ni—SiO 2 =15/(1.1-100) respectively. The evaluation results of the catalysts thus prepared were also shown in table 1. 
       Example 5, 6 
       [0038]    The catalysts were prepared according to the experiment steps described in Example 1, but the weight of carrier SiO 2  to be plated was respectively 8 g and 6 g. The weight ratio of every content of the catalysts gained was K 2 MoO 4 /Ni—SiO 2 =15/(5.5-100) and K 2 MoO 4 /Ni—SiO 2 =15/(7.3-100), respectively. The evaluation results of the catalysts thus prepared are also shown in table 1. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
             
             
               
                   
               
               
                 performance of the catalysts K 2 MoO 4 /Ni—SiO 2  in examples 1-6 
               
             
          
           
               
                   
                 selectivity 
                   
                 CO % 
               
             
          
           
               
                 examples 
                 K 2 MoO 4 /Ni—SiO 2   
                 CH 4   
                 CH 3 SH 
                 COS 
                 CO 2   
                 CO 2 /CH 3 SH 
                 conversion 
               
               
                   
               
             
          
           
               
                 1 
                 15/(4.4-100) 
                 0.0226 
                 46.84 
                 18.91 
                 34.02 
                 0.7265 
                 56.84 
               
               
                 2 
                 15/(2.2-100) 
                 0.0216 
                 46.31 
                 20.33 
                 33.14 
                 0.7156 
                 63.45 
               
               
                 3 
                 15/(1.5-100) 
                 0.0202 
                 46.61 
                 20.67 
                 32.70 
                 0.7017 
                 65.61 
               
               
                 4 
                 15/(1.1-100) 
                 0.0130 
                 43.37 
                 24.91 
                 31.70 
                 0.7311 
                 49.16 
               
               
                 5 
                 15/(5.5-100) 
                 0.0207 
                 46.70 
                 19.01 
                 34.27 
                 0.7338 
                 56.57 
               
               
                 6 
                 15/(7.3-100) 
                 0.0196 
                 46.85 
                 19.14 
                 34.99 
                 0.7255 
                 55.46 
               
               
                   
               
             
          
         
       
     
       Example 7, 8, 9, 10, 11 
       [0039]    The catalysts were prepared according to the experiment steps described in Example 3, but the weight ratio of K 2 MoO 4 /support varied from 5/100, 10/100, 15/100, 20/100, 25/100. The weight ratio of every component of the catalysts gained was K 2 MoO 4 /Ni—SiO 2 =5/(1.5-100), K 2 MoO 4 /Ni—SiO 2 =10/(1.5-100), K 2 MoO 4 /Ni—SiO 2 =15/(1.5-100), K 2 MoO 4 /Ni—SiO 2 =20/(1.5-100), K 2 MoO 4 /Ni—SiO 2 =25/(1.5-100) respectively. The evaluation results of the catalysts thus prepared were also shown in table 2. 
       Example 12 
       [0040]    (1) 0.667.0 g of NiSO 4 .7H 2 O and 0.667 g of Na 3 C 6 H S O 7 .2H 2 O were dissolved into 50 ml of distilled water successively to produce a plating solution, keeping stirring for 10 minutes, then 1.0 g of (NH 4 ) 2 SO 4  and 1.0 g of NaH 2 PO 4 .H 2 O were added one after another to the solution obtained above, stirring for another 20 minutes, followed by adding some NH 3 .H 2 O to adjust the pH of the solution to 9.0; finally, distilled water was added to adjust the volume of the solution to 100 ml in such a way that the concentration of NiSO 4  in the plating solution was 4.12 g/l; 
         [0041]    (2) 10 g of clean SiO 2  were immersed in 20 ml of 4.5 mol/l H 2 SO 4 +0.88 mol/l H 2 O 2 (1:1) solution for 5 minutes under agitating, and then washed for three times with distilled water, followed by immersing the carrier SiO 2  in 20 ml of 0.1 g/l PdCl 2 /HCl solution, at the same time keeping ultrasonically agitating for 30 minutes, and then washed for three times with distilled water; the next step was to immerse the activated carrier SiO 2  in 10 ml of 30 g/l NaH 2 PO 4  solution, at the same time agitating for 10 seconds; finely repeated the reduced experiment step again to produce an activated carrier SiO 2 . 
         [0042]    (3) The electroless plating process was carried out by immersing the activated carrier SiO 2  in the plating solution prepared in step (2) at 42° C. for 30 minutes. After plating, the Ni-plated SiO 2  was washed with distilled water four times and then dried at 110° C. for 6 hours. The weight ratio of the two contents of the support thus prepared was Ni—SiO 2 =1.5-100. 
         [0043]    (4) 0.496 g of K 2 MoO 4  and 1.0 ml of NH 3 .H 2 O were dissolved in 5 ml of distilled water to generate an impregnation solution; then 0.5 g of tartaric acid and 0.135 g of Ni(NO 3 ) 2-6 H 2 O were added to the K 2 MoO 4  solution, the pH value of the K 2 MoO 4  solution was measured to be at 9; then 3 g of support nickel-plated SiO 2  (30-45 meshes) produced in step (3) was soaked in the impregnation solution at room temperature for 12 hours, then dried at 110° C. for 6 hours. The weight ratio of every component of the catalyst thus prepared was K 2 MoO 4 /NiO/Ni—SiO 2 =15/1.0/(1.5-100). The evaluation result of the catalyst thus prepared is shown in table 3. 
       Example 13 
       [0044]    The catalyst was prepared according to the experiment steps described in Example 12, but 0.1346 g of Co (NO 3 ) 2-6 H 2 O substituted for 0.135 of Ni(NO 3 ) 2-6 H 2 O. The weight ratio of every component of the catalyst thus prepared was K 2 MoO 4 /CoO/Ni—SiO 2 =15/1.0/(1.5-100). The evaluation result of the catalyst thus prepared is also shown in table 3 
       Example 14 
       [0045]    The catalyst was prepared according to the experiment steps described in Example 1, but NiSO 4 .7H 2 O for preparing plating solution was replaced by CoSO 4 .7H 2 O, the amount of CoSO 4 .7H 2 O is the same as that of NiSO 4 .7H 2 O, but the Ph value of the plating solution was adjusted by NH 3 .H 2 O to 12; the plating process of the activated carrier SiO 2  was carried out at 80° C. The weight ratio of every component of the catalyst gained was K 2 MoO 4 /(Co—SiO 2 )=15/(4-100). The evaluation result of the catalyst thus prepared was shown in table 4 
       Example 15 
       [0046]    The catalyst was prepared according to the experiment steps described in Example 12, but 0.667 g of NiSO 4 .7H 2 O for preparing plating solution was replaced by 0.667 g of CoSO 4 .7H 2 O; while the quantity of Ni(NO 3 ) 2-6 H 2 O for preparing promoter Me x O y  was 0.117 g. The weight ratio of every component of the catalyst gained was K 2 MoO 4 /NiO/Co—SiO 2 =15/1/(1.5-100). The evaluation result of the catalyst thus prepared is also shown in table 4 
       Example 16 
       [0047]    The catalyst was prepared according to the experiment steps described in Example 15, but 0.117 g of Ni(NO 3 ) 2 .6H 2 O for preparing promoter Me x O y  was replaced by 0.117 g of Co(NO 3 ) 2-6 H 2 O. The weight ratio of every component of the catalyst gained was K 2 MoO 4 /CoO/Co—SiO 2 =15/1/(1.5-100). The evaluation result of the catalyst thus prepared is also shown in table 4 
       Example 17 
       [0048]    The catalyst was prepared according to the experiment steps described in Example 1, but 0.45 g K 2 MoO 4  and 0.5 g tartaric acid were replaced by 3.00 g of (NH 4 ) 6 Mo 7 O 24 .4H 2 O plus 0.45 g of KNO 3  and 0.5 g of citric acid respectively. The weight ratio of every component of the catalyst gained was MoO 3 /K 2 O/(Ni—SiO 2 )=11/4/(4-100). The evaluation result of the catalyst thus prepared is shown in table 5 
       Example 18 
       [0049]    The catalyst was prepared according to the experimental steps described in Example 12, but 0.496 g K 2 MoO 4  was replaced by 3.00 g of (NH 4 ) 6 Mo 7 O 24 .4H 2 O plus 0.22 g of K 2 CO 3 . The weight ratio of every component of the catalyst gained was MoO 3 /K 2 O/NiO/(Ni—SiO 2 )=11/4/0.25/(1.5-100). The assay result of the catalyst thus prepared was shown in table 5. 
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
             
             
               
                   
               
               
                 performance of catalysts K 2 MoO 4 /Ni—SiO 2  in examples 7-11 
               
             
          
           
               
                   
                 Selectivity, % 
                   
                 CO 
               
             
          
           
               
                 examples 
                 K 2 MoO 4 /(Ni—SiO 2 ) 
                 CH 4   
                 CH 3 SH 
                 COS 
                 CO 2   
                 CO 2 /CH 3 SH 
                 Conversion, % 
               
               
                   
               
             
          
           
               
                 7 
                  5/(1.5-100) 
                 0.0956 
                 28.74 
                 40.12 
                 31.04 
                 1.080 
                 30.21 
               
               
                 8 
                 10/(1.5-100) 
                 0.0353 
                 38.13 
                 28.64 
                 33.20 
                 0.871 
                 43.15 
               
               
                 9 
                 15/(1.5-100) 
                 0.0282 
                 46.61 
                 16.79 
                 36.57 
                 0.785 
                 65.61 
               
               
                 10 
                 20/(1.5-100) 
                 0.0339 
                 35.96 
                 33.47 
                 30.23 
                 0.841 
                 58.96 
               
               
                 11 
                 25/(1.5-100) 
                 0.0496 
                 30.38 
                 38.24 
                 31.33 
                 1.030 
                 59.63 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 3 
               
             
             
               
                   
               
               
                 performance of catalysts K 2 MoO 4 —NiO/Ni—SiO 2  in examples 10-11 
               
             
          
           
               
                   
                 Selectivity, % 
                   
                 CO % 
               
             
          
           
               
                 examples 
                 catalysts 
                 CH 4   
                 CH 3 SH 
                 COS 
                 CO 2   
                 CO 2 /CH 3 SH 
                 conversion 
               
               
                   
               
             
          
           
               
                 12 
                 K 2 MoO 4 /NiO/(Ni—SiO 2 ) = 
                 0.0257 
                 37.63 
                 19.94 
                 42.40 
                 1.127 
                 69.26 
               
               
                   
                 25/1.7/(1.5-100) 
               
               
                 13 
                 K 2 MoO 4 /CoO/(Ni—SiO 2 ) = 
                 0.0214 
                 37.64 
                 19.10 
                 43.24 
                 1.148 
                 62.58 
               
               
                   
                 25/2.6/(1.5-100) 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
             
             
               
                   
               
               
                 performance of catalysts K 2 MoO 4 /Co—SiO 2  in examples 14-16 
               
             
          
           
               
                   
                 Selectivity, % 
                   
                 CO % 
               
             
          
           
               
                 examples 
                 catalysts 
                 CH 4   
                 CH 3 SH 
                 COS 
                 CO 2   
                 CO 2 /CH 3 SH 
                 conversion 
               
               
                   
               
             
          
           
               
                 14 
                 K 2 MoO 4 /(Co—SiO 2 ) = 
                 0.01675 
                 42.42 
                 17.05 
                 40.51 
                 0.9550 
                 36.33 
               
               
                   
                 (15/4.4-100) 
               
               
                 15 
                 K 2 MoO 4 /NiO/(Co—SiO 2 ) = 
                 0.01507 
                 46.15 
                 23.66 
                 30.17 
                 0.6538 
                 24.77 
               
               
                   
                 15/1.0/(1.5-100) 
               
               
                 16 
                 K 2 MoO 4 /CoO/(Co—SiO 2 ) = 
                 0.01459 
                 35.74 
                 16.91 
                 34.33 
                 0.7705 
                 24.64 
               
               
                   
                 15/1/(1.5-100) 
               
               
                   
               
             
          
         
       
     
         [0000]    
       
         
               
             
               
               
               
               
             
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 5 
               
             
             
               
                   
               
               
                 performance of catalysts K 2 MoO 4 —NiO/Ni—SiO 2  in examples 17-18 
               
             
          
           
               
                   
                 Selectivity, % 
                   
                 CO % 
               
             
          
           
               
                 examples 
                 catalysts 
                 CH 4   
                 CH 3 SH 
                 COS 
                 CO 2   
                 CO 2 /CH 3 SH 
                 conversion 
               
               
                   
               
             
          
           
               
                 17 
                 MoO 3 /K 2 O/(Ni—SiO 2 ) = 
                 0.0226 
                 45.57 
                 19.91 
                 34.22 
                 0.7466 
                 56.84 
               
               
                   
                 11/4/(4.4-100) 
               
               
                 18 
                 MoO 3 /K 2 O/NiO/Ni—SiO 2  = 
                 0.0283 
                 39.55 
                 22.21 
                 38.20 
                 0.9658 
                 60.32 
               
               
                   
                 11/4/0.25/(1.5-100)