Glycerol → Acrolein

Participants

Reaction Steps

A gas stream at 331° C. under 2.0 bar (50.3 t/h, 34.5% glycerol, 34.5% water, 23.7% nitrogen, 7.2% oxygen) is sent to a multitube fixed bed reactor (10) containing a heterogeneous dehydration catalyst coupled with a molten salt bath. A gas stream (14) leaves this reactor at 320° C. under 1.7 bar (50.3 t/h, 47.9% water, 23.7% nitrogen, 5.0% oxygen, 16.4% acrolein, 1.6% acetaldehyde, 1.4% CO, 1.1% CO2). This stream is cooled to 151° C. in a heat exchanger (15) and sent to the bottom of an absorption column (11) which comprises four theoretical stages. The gas stream (16) leaving the top of this absorption column at 102° C. is sent to a partial condenser (17) which cools it to 79° C., and then to a flash pot (18) which separates the gas phase (24) from the liquid phase (19). This liquid phase (19) is sent to the top of the absorption column (11). A liquid phase (3) is drawn off from the bottom of the absorption column, at 103° C. (20.4 t/h, 94.3% water, 1.4% acetic acid, 1.0% formic acid). This liquid phase (3) is sent to the top of a stripping column (20) comprising 8 trays, into which 4.4 t/h of air (21) is injected at the bottom at 90° C. under 1.7 bar. An aqueous stream (22) is recovered from the bottom of this stripping column (55° C., 18.6 t/h, 94.5% water, 1.3% acetic acid, 1.0% formic acid). The gas stream (23) recovered at the top of the stripping column is mixed with the gas phase (24) from the flash pot previously described (79° C., 29.9 t/h, 39.9% N2, 27.2% acrolein, 8.4% oxygen, 16.2% water, 2.7% acetaldehyde, 2.4% carbon monoxide, 1.8% carbon dioxide) and with a gas stream (6) (33.5 t/h, 77.2% nitrogen, 3.6% oxygen, 7.2% water, 5.4% carbon dioxide, 4.5% carbon monoxide). The mixture is heated to 160° C., and then injected into a second multitube reactor (12) comprising an oxidation catalyst. At the outlet of this reactor, a gas stream (7) is obtained at 245° C. under 1.4 bar (69.6 t/h, 59.1% nitrogen, 13.1% water, 14.7% acrylic acid, 2.8% oxygen, 4.2% carbon dioxide, 3.4% carbon monoxide, 1.6% acetic acid). This stream is cooled to 157° C. and then injected at the bottom of the absorption column (13). At the top of this column, the gas stream is partially condensed in the heat exchanger (24), and then sent to a separator pot (25) which produces a liquid phase (26) and a gas phase (8) (55.6 t/h, 53° C., 77.2% nitrogen, 3.6% oxygen, 7.2% water, 5.4% carbon dioxide, 4.5% carbon monoxide). The liquid phase is returned to the column (13). The gas phase is partially recycled upstream of the reactor (12) via the stream (6). At the bottom of the absorption column (13), a stream (9) of concentrated acrylic acid is obtained (15.6 t/h, 64.1% acrylic acid, 34.4% water).

Provenance & Evidence