Methods for recovering PU foam waste using fluid

Abstract

A method for recovering PU foam waste using fluid includes the following steps: Step S1, preparing PU foam waste and an alcohol solvent, wherein the alcohol solvent is an alcohol with three or fewer carbon atoms; Step S2, feeding the PU foam waste and the alcohol solvent separately into a reaction device for heating, wherein the heating temperature of the reaction device is between 100°C and 300°C, so that the alcohol solvent is in a critical state, and the PU foam waste is cracked and carbonized by the alcohol solvent in the critical state, to obtain a recovered carbonized material and a polyol recovery liquid; thereby, this method can significantly reduce the pollution of PU foam waste, reduce energy consumption, provide environmental protection and high value-added effects, and achieve environmental benefits such as carbon reduction, net-zero emissions, and circular economy.

Claims

1. A method for recovering PU foaming waste using fluid, comprising the following steps: Step S1, preparing PU foaming waste and an alcohol solvent, wherein the alcohol solvent is an alcohol with three or fewer carbon atoms; and Step S2, feeding the PU foaming waste and the alcohol solvent separately into a reaction device and heating them, wherein the heating temperature of the reaction device is between 100°C and 300°C, so that the alcohol solvent is in a critical state, and the PU foaming waste is cracked and carbonized by the alcohol solvent in the critical state to obtain a recovered carbonized material and a polyol recovery liquid, wherein the recovered carbonized material satisfies the following condition: 6500 < HHVs < 8000, where HHVs is the calorific value (kcal / kg) of the recovered carbonized material; and the polyol recovery liquid satisfies the following condition: 4500 < HHVlq < 6500, where HHVlq is the calorific value (kcal / L) of the polyol recovery liquid.

2. The method for recovering PU foaming waste using fluid as described in claim 1, wherein the solid-liquid ratio (g / ml) of the PU foaming waste to the alcohol solvent is between 1:1 and 1:5, the reaction apparatus is heated to the heating temperature and the holding time is controlled between 0 and 4 hours, and the pressure of the reaction apparatus is between 5 MPa and 8 MPa.

3. The method for recovering PU foam waste using fluid as described in claim 1, wherein the carbon content of the polyol recovery liquid is between 30 wt% and 60 wt%, the carbon content of the recovered carbonized material is at least 60 wt%, and the carbon content of the polyol recovery liquid is lower than the carbon content of the recovered carbonized material.

4. The method for recovering PU foam waste using fluid as described in claim 1, wherein the recovered carbonized material satisfies the following conditions: 0.08 < Os / Cs < 0.30, 1.20 < Hs / Cs < 2.00, wherein... Os represents the number of oxygen atoms in the recycled carbonized material, Cs represents the number of carbon atoms in the recycled carbonized material, and Hs represents the number of hydrogen atoms in the recycled carbonized material.

5. The method for recovering PU foaming waste using fluid as described in claim 1, wherein the polyol recovery liquid satisfies the following conditions: 0.30 < Olq / Clq < 0.70, 1.50 < Hlq / Clq < 3.00, wherein... Olq represents the number of oxygen atoms in the polyol recovery liquid, Clq represents the number of carbon atoms in the polyol recovery liquid, and Hlq represents the number of hydrogen atoms in the polyol recovery liquid.

6. The method for recovering PU foaming waste using fluid as described in claim 1, wherein the reaction apparatus has a stirrer capable of stirring and mixing the PU foaming waste with the alcohol solvent, and the stirrer speed of the reaction apparatus is between 50 rpm and 350 rpm.

7. The method for recovering PU foaming waste using fluid as described in claim 1, wherein the PU foaming waste and the alcohol solvent are fed into the reaction apparatus in batches, and the amount of the PU foaming waste and the alcohol solvent fed each time is 10% to 90% of the capacity of the reaction apparatus.

8. The method for recovering PU foaming waste using fluid as described in claim 1, wherein in step S2, a silicon-containing material is fed together with the PU foaming waste and the alcohol solvent into the reaction apparatus for mixing, the heating temperature of the reaction apparatus being between 250°C and 300°C, the PU foaming waste being pyrolyzed and carbonized into the recovered carbonized material, the recovered carbonized material being mixed with the silicon-containing material as a carbon-silicon mixture.

9. The method for recovering PU foaming waste using fluid as described in claim 8, wherein the weight ratio of the PU foaming waste to the silicon-containing material is between 1:1 and 1:5, the solid-liquid ratio (g / ml) of the combination of the PU foaming waste and the silicon-containing material to the alcohol solvent is between 1:0.5 and 1:2, the reaction apparatus is heated to the heating temperature and the holding time is controlled between 0 and 4 hours, and the pressure of the reaction apparatus is between 5 MPa and 8 MPa.

10. The method for recovering PU foam waste using fluid as described in claim 8, wherein step S3 is included after step S2, in which the carbon-silicon mixture is removed from the reaction apparatus and dried, and after drying, the carbon-silicon mixture is placed in a high-temperature reaction furnace and heated to at least 1000°C, so that the recovered carbonized material and the silicon-containing material in the carbon-silicon mixture undergo a thermal carbon reduction reaction to synthesize a recycled silicon carbide product.

11. The method for recovering PU foam waste using fluid as described in claim 10, wherein the carbon atom content of the recycled silicon carbide product is between 35 at% and 60 at%, and the silicon atom content of the recycled silicon carbide product is between 10 at% and 20 at%.

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