Regarding propyl groups in MTBE products
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After our MTBE plant has been in operation for some time, minor amounts of propylene are always detected in the product analysis, at levels below 1%. Given the conditions under which propylene is formed, it seems difficult to achieve such low levels. However, the conditions required for dimethyl ether synthesis are not as stringent. The thermodynamic reaction for the formation of dimethyl ether from CH3OH via dehydration is as follows: 2CH3OH ----(CH3)2O + H2O – 23.4 kJ/mol. Is it difficult to distinguish between propylene and dimethyl ether in analytical tests? Those who have encountered similar situations are welcome to join the discussion.
Peak R.T. “Mass percentage (%)” Name Quality Remarks 1 1.432 0.038 2 1.973 0.076 Isobutylene 90 C4 hydrocarbons 3 2.254 0.025 Methanol 2 Alcohols 4 4.119 0.064 4-Methyl-1-pentene 64 C6 hydrocarbons 5 4.233 0.167 2,3-Dimethylbutane 91 C6 hydrocarbons 6 4.303 0.975 2-Methylpentane 91 C6 hydrocarbons 7 4.514 0.753 tert-Butanol (TBA) 90 Alcohols 8 4.757 81.640 Methyl tert-butyl ether (MTBE) 78 Main component 9 5.109 0.136 1-Hexene 94 C6 hydrocarbons 10 5.282 0.232 n-Hexane 90 C6 hydrocarbons 11 5.476 1.575 Methyl sec-butyl ether 91 Ethers 12 5.633 0.094 2-Hexene 94 C6 hydrocarbons 13 5.730 0.086 4-Methyl-2-pentene 91 C6 hydrocarbons 14 5.903 0.046 3-Methyl-2-pentene 94 C6 hydrocarbons 15 6.071 0.054 2-Hexene 87 C6 hydrocarbons 16 6.320 0.089 3-Methyl-2-pentene 94 C6 hydrocarbons 17 6.487 0.049 2,4-Dimethylpentane 78 C7 hydrocarbons 18 6.639 0.387 Methylcyclopentane 52 C6 hydrocarbons 19 7.715 0.081 2-Butanol 83 Alcohols 20 8.066 0.061 1,3,3-Trimethylcyclopropene 90 C6 hydrocarbons 21 8.607 0.261 2-Methylhexane 94 C7 hydrocarbons 22 8.817 0.133 2,3-Dimethylpentane 76 C7 hydrocarbons 23 9.245 0.226 3-Methylhexane 94 C7 hydrocarbons 24 9.731 0.066 Benzene 95 C6 25 9.996 0.094 1,3-Dimethylcyclopentane 91 C7 hydrocarbons 26 10.396 9.386 Methyl tert-amyl ether 90 Ethers 27 11.066 0.127 n-Heptane 62 C7 hydrocarbons 28 11.612 0.063 2-Methyl-2-hexene 64 C7 hydrocarbons 29 12.180 0.061 2,4,4-Trimethyl-1-pentene 80 C8 hydrocarbons 30 12.861 0.122 Methylcyclohexane 81 C7 hydrocarbons 31 13.229 0.046 1-Octene 25 C8 hydrocarbons 32 13.413 0.037 2,4-Dimethylhexane 72 C8 hydrocarbons 33 13.629 0.021 Ethylcyclopentane 95 C7 hydrocarbons 34 15.164 0.057 1,4-Dimethylcyclohexane 30 C8 hydrocarbons 35 15.429 0.102 2-Methylheptane 94 C8 hydrocarbons 36 15.532 0.034 4-Methylheptane 86 C8 hydrocarbons 37 15.748 0.036 Dimethyl sulfide 91 Sulfides 38 15.910 0.123 2,4-Dimethylhexane 64 C8 hydrocarbons 39 16.056 0.033 3-Octanol 40 Alcohols 40 16.181 0.119 2,3-Dimethoxy-2-methylbutane 64 Ethers 41 16.694 0.281 Toluene 87 C7 hydrocarbons 42 17.023 0.051 1,3-Dioxane 9 Cyclic ethers 43 17.375 0.036 n-Octane 60 C8 hydrocarbons 44 19.241 0.028 2,5-Dimethylheptane 72 C9 hydrocarbons 45 19.333 0.029 Ethylcyclohexane 22 C7 hydrocarbons 46 20.625 0.097 4-Methyloctane 68 C8 hydrocarbons 47 20.971 0.052 3-Methyloctane 59 C8 hydrocarbons 48 21.165 0.022 2-Methoxy-2,3,5,5-tetramethylhexane 9 Ethers 49 21.484 0.066 Ethylbenzene 87 C8 hydrocarbons 50 21.868 0.369 p-Xylene 97 C8 hydrocarbons 51 22.209 0.033 n-Nonane 62 C9 hydrocarbons 52 22.576 0.048 2-Methyl-2,4-dimethoxybutane 64 Ethers 53 23.025 0.127 o-Xylene 97 C8 hydrocarbons 54 24.398 0.064 Ethyl sulfide 96 Sulfides 55 24.879 0.026 2-Methylnonane 59 C10 hydrocarbons 56 25.166 0.028 3-Methylnonane 59 C10 hydrocarbons 57 25.717 0.132 1-Ethyl-2-methylbenzene 95 C9 hydrocarbons 58 25.771 0.042 1,2,3-Trimethylbenzene 90 C9 hydrocarbons 59 25.993 0.075 1,2,4-Trimethylbenzene 93 C9 hydrocarbons 60 26.534 0.037 1-Ethyl-4-methylbenzene 90 C9 hydrocarbons 61 27.053 0.219 1,3,5-Trimethylbenzene 97 C9 hydrocarbons 62 28.247 0.046 1,2,4-Trimethylbenzene 90 C9 hydrocarbons 63 28.761 0.028 Dihydronaphthalene 92 C9 hydrocarbons 64 29.015 0.031 1-Methyl-3-propylbenzene 91 C10 hydrocarbons 65 29.242 0.047 1-Ethyl-3,5-dimethylbenzene 94 C10 hydrocarbons 66 29.994 0.026 2-Ethyl-1,4-dimethylbenzene 94 C10 hydrocarbons 67 30.296 0.043 2-Ethyl-1,4-dimethylbenzene 90 C10 hydrocarbons 68 31.437 0.021 1,2,4,5-Tetramethylbenzene 87 C10 hydrocarbons 69 31.589 0.036 1,2,3,5-Tetramethylbenzene 90 C10 hydrocarbons 70 32.735 0.038 1-Methylallylbenzene 70 C10 hydrocarbons 71 34.454 0.022 Naphthalene 80 C10 hydrocarbons 72 37.779 0.030 2-Methylnaphthalene 90 C11 hydrocarbons Our products have been analyzed, and these are the results. I hope this information is helpful to you!