Process for synthesis of acrolein
An object of the present invention is to provide a technology which can suppress the blockage and abrasion of pipes and devices caused by the production of by-products and stably synthesize acrolein at a high yield, under a condition in which energy efficiency is improved by an elevated concentration of glycerol in a reaction liquid, in a process for synthesis of acrolein by reacting supercritical water and an acid with glycerol. An embodiment of the present invention includes: setting a concentration of glycerol in the reaction liquid at 30% by weight or lower; also cooling the reaction liquid to a temperature between a temperature (300° C. or lower) at which the reaction stops and a temperature (100° C. or higher) at which tar contained in the reaction liquid can keep a state in which its viscosity is sufficiently low; then separating and removing carbon particles from the reaction liquid; subsequently cooling the reaction liquid to a temperature which is a boiling point of water or lower and at which the tar component in the reaction liquid does not adhere to devices; and then decompressing the cooled reaction liquid.
1. A process for synthesis of acrolein by reacting supercritical water and an acid with glycerol, the process comprising: setting a concentration of glycerol in a reaction liquid at 15-30% by weight; also cooling the reaction liquid to 200 to 300° C. in a first cooling; then separating and removing a solid component comprised in the reaction liquid; subsequently cooling the reaction liquid to 60 to 100° C. in a second cooling; and then decompressing the cooled reaction liquid.
2. The process for synthesis according to claim 1 , wherein a proton concentration [H + ] (% by weight) in the reaction liquid is in a range expressed by the following expression using a glycerol concentration [G] (mM):
5 ×√{square root over ([G])}<[H + ]<20 ×√{square root over ([G])} [Formula 1].
3. The process for synthesis according to claim 1 , wherein a reaction time t is in a range expressed by the following expression using the glycerol concentration [G] (mM) in the reaction liquid:
3.75
[
G
]
<
t
<
1.5
[
G
]
.
[
Formula
2
]
4. The process for synthesis according to claim 1 , wherein a pore diameter of a filter for separating and removing the solid component is 40 micrometers or less.
5. The process for synthesis according to claim 1 , wherein the concentration of glycerol is higher than 15% by weight.
6. The process for synthesis according to claim 2 , wherein a reaction time t is in a range expressed by the following expression using the glycerol concentration [G] (mM) in the reaction liquid:
3.75
[
G
]
<
t
<
1.5
[
G
]
.
[
Formula
2
]
7. The process for synthesis according to claim 1 , wherein the first cooling comprises directly mixing a cooling fluid with the reaction liquid.
8. The process for synthesis according to claim 7 , wherein the cooling fluid comprises water.