); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (R.Y.) [PERSON]  
1 Chongqing Unis Chemical Company Ltd., Chongqing 401121, China; [EMAIL_ADDRESS] (Z.C. ); [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (R.Y.) [PERSON]  
1 Chongqing Unis Chemical Company Ltd., Chongqing 401121, China; [EMAIL_ADDRESS] (Z.C. ); [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (R.Y.) [PERSON]  
1 Chongqing Unis Chemical Company Ltd., Chongqing 401121, China; [EMAIL_ADDRESS] (Z.C. ); [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (R.Y.) [PERSON]  
1 Chongqing Unis Chemical Company Ltd., Chongqing 401121, China; [EMAIL_ADDRESS] (Z.C. ); [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (R.Y.) [PERSON]  
1 Chongqing Unis Chemical Company Ltd., Chongqing 401121, China; [EMAIL_ADDRESS] (Z.C. ); [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (Y.L. ); [EMAIL_ADDRESS] (R.Y.) [PERSON]  
1 Chongqing Unis Chemical Company Ltd., Chongqing 401121, China; [EMAIL_ADDRESS] (Z.C. ); [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (Y. (Equation (1)) [7]; (2) the methanol vulcanization process (Equation (2)) [8; 9]; (3) the methanethiol vulcanization process (Equation (3)) [10; 11]; and (4) the methyl mercaptan oxidation process which is also called Merox process (Equation (4)) [12]:  
\[(CH_{3}O)_{2}SO_{2}+Na_{2}S+S\to CH_{3}SSCH_{3}+Na_{2}SO_{4} \tag{1}\]  
\[2 CH_{3}OH+S+H_{2}S\overset{catalyst}{\rightarrow}CH_{3}SSCH_{3}+2H_{2}O \tag{2}\]  
\[2 CH_{3}SH+S\overset{catalyst}{\rightarrow}CH_{3}SSCH_{3}+H_{2}S \tag{3}\]  
\[4 CH_{3}SH+O_{2}\overset{catalyst}{\rightarrow}2 CH_{3}SSCH_{3}+2H_{2}O \tag{4}\]  
Compared with other processes, the Merox process shows many advantages, such as high yield and purity of DMDS products, no usage of highly toxic raw materials, etc. However, the traditional Merox process is a gas-gas reaction, so it has a high risk of explosion and pollutes the environment because of the exhaust gas produced in the process. Additionally, the process has very high requirements for reactor quality, airtightness, and pressure endurance. In order to solve these problems, engineers refined the Merox process of the gas-gas reaction into a gas-liquid reaction using sodium methylmercapaptide (SMM) as the reagent, as shown in Equations (5) and (6) [13; 14; 15]:  
\[CH_{3}SH+NaOH\to CH_{3}SNa+H_{2}O \tag{5}\]  
\[4 CH_{3}SNa+O_{2}+2H_{2}O\overset{catalyst}{\rightarrow}2 CH_{3}SSCH_{3}+4 NaOH \tag{6}\]  
Unlike the catalysts used in the reaction shown in Equation (4) of MgO or Na\({}_{2}\)O [12], the commonly-used catalysts in the reaction shown in Equation (6) are metal phthalocyanines and their derivatives, such as sulfonated cobalt phthalocyanine (CoPcS) [13; 14], cobalt tetraaminophthalocyanine (CoTAPc) [16], etc. The former is the most widely-used catalyst because of its lower cost, high efficiency, and high selectivity of the catalytic performance. However, the free CoPcS catalyst is hydrosoluble, therefore, it very easily gets into the DMDS product, creating separation problems between the catalyst and the product. This leads to high cost of post-treatment of DMDS products, and the catalyst will not be able to be reused. In order to solve these problems, the researchers supported the metal phthalocyanines on solid supports, such as activated carbon (AC) [17; 18], activated carbon fiber [19; 20], viscose fibers [21], carbon nanotubes [22], graphene oxide [23], silicas [24], mineral carriers [25; 26], TiO\({}_{2}\) [27; 28], molecular sieves [29], etc. In contrast, AC is the best choice for industrial applications because of its special advantages of high surface area, well-developed pore structure, high absorptivity, and stability. However, the AC-supported sulfonated cobalt phthalocyanine (AC-CoPcS) catalyst is commonly prepared by the physical method of dipping [13; 14; 17] or dispersion [18]. There still exists the problem of loss of the active ingredient of the supported catalyst, resulting in dissatisfactory reuse performance.