Catalytic formulation for producing propylene cyclic carbonate from carbon dioxide using a potassium iodide catalyst

Abstract

This invention is related to the synthesis of organic carbonates from carbon dioxide and epoxides. It is particularly focused on the production of propylene cyclic carbonate from propylene oxide. The proposed catalytic materials includes a support made of aluminum oxyhydroxide (Catapal B®), nitric acid, acetic acid and/or phosphoric acid. An important stage is the physical and chemical conditioning of the catalytic materials and to this end, experimental methodologies such as spheronization and thermal treatments were implemented prior the evaluation process.

Claims

1. A catalytic formulation comprising: a) a support material made of an aluminum oxyhydroxide or aluminum oxide within a weight ratio between 30 and 90%; b) a carbonaceous material in a weight ratio between 1 and 60%; c) a polymeric material soluble in water or in slightly acid solutions with the presence of oxydrile groups, within a weight ratio between 1 and 45%; d) a salt promoting the presence of phosphate ions within a weight ratio between 1 and 30%; e) an aqueous acid agglutination agent at a weight ratio between 1 and 15%, and wherein the aqueous the acid agglutination agent is selected from the group consisting of aqueous solutions of formic acid, acetic acid, nitric acid, and mixtures thereof; f) an alkaline metal halogen within a weight ratio between 1 and 80%, and wherein the alkaline metal halogen comprises potassium iodide; g) the catalyst promoting a cycloaddition reaction between carbon dioxide and propylene oxide for producing propylene cyclic carbonate; and h) the catalyst having been subjected to a ramped calcination heating procedure starting at room temperature to a final temperature of 450° C. followed by cooling to room temperature.

2. The catalytic formulation according to claim 1, where the polymeric material is selected from the group consisting of poly(vinyl alcohol), chitosan, polyacrylamide, polyacrylates, and combinations thereof.

3. The catalytic formulation according to claim 1, where the phosphate salt is selected from the group consisting of dihydrogen phosphate, monoacid phosphate, sodium phosphate, potassium phosphate, and combinations thereof.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 shows the general reaction scheme for the cycloaddition of CO.sub.2 to epoxides and the formation of cyclic carbonates, where the methyl substituent can be replaced by diverse functional groups. In the particular case of the formation of propylene carbonate, such substituent is H.

(2) FIG. 2 displays the behavior pattern of the CO.sub.2 pressure as a function of the reaction time for the cycloaddition of CO.sub.2 in a batch reactor. From continuous monitoring of the pressure, it is adjusted manually to keep a nominal value of 29.5 kg/cm.sup.2 of CO.sub.2. Then, despite the CO.sub.2 amount diminishes during the reaction, the adjustment to a constant pressure value ensures the driving force to carry out the reaction to be practically constant.

(3) FIG. 3 shows the distribution of compound families that are obtained from the experimental evaluation of the cycloaddition reaction in a packed bed tubular reactor. The grouping of glycol compounds was carried out, giving as a result, a set for propylene glycol, di-propylene glycol and tri-propylene glycol (here even compounds known as tetraglymes were inserted). In addition, the performance of the interest product is presented: propylene carbonate.

(4) The production of propylene carbonate follows a trend with a diminution of its concentration between the reaction times 400 and 1500 min. From this point, it presents a more or less stable performance up to 2400 min of evaluation. It is important to achieve homogeneous behavior and diminish the presence of subproducts and to this end, the following adjustments were performed: reduction of the concentration of the catalyst active phase and improvement of the heat transfer during the reaction in order to avoid the temperature increase in the packed bed. For this experimental run, it reached 200° C. above the desired reactor temperature. Another possibility is to employ a continuous flow isothermal reactor like the one shown in FIG. 4.

(5) FIG. 4 illustrates a reactor of the type Robinson-Mahoney. This reactor shows the particular feature of having an annular basket (A) for packing the catalytic bed and in the center there is a mechanical stirrer (B) and a cooling jacket (C) that ensures the elimination of hot spots on the catalyst surface.

(6) FIG. 5 displays the results of diverse experimental runs using the previously described configuration. The results after 16 h of reaction and using two catalysts with different concentrations of active phase, 20 and 38 wt. % of KI, are shown.

(7) Experimental runs were also performed with base materials (without active phase) and after 16 h of reaction, the yield was practically negligible (1.5%); this result is not shown in the plot.

(8) FIG. 6 shows the results of different experimental runs using the configuration of the Robinson-Mahoney reactor. The results after 20 h of reaction and using two catalysts with different concentrations of active phase, 20 and 38 wt. % of KI, are shown.

DETAILED DESCRIPTION OF THE INVENTION

(9) This invention deals with the synthesis of propylene cyclic carbonate from CO.sub.2 and propylene oxide using catalysts whose active phase is KI supported on aluminum oxyhydroxide (Catapal B®). The catalytic formulation consists of different materials like: NaH.sub.2PO.sub.4, poly(vinyl alcohol), activated carbon (AC), nitric acid, acetic acid, and phosphoric acid. The physical and chemical conditioning of the catalytic materials was also necessary; to this end, experimental methodologies such as spheronization and thermal treatments were implemented prior the evaluation process.

(10) In one embodiment, the invention is directed to a catalytic formulation for a cycloaddition reaction between carbon dioxide and propylene oxide for producing propylene cyclic carbonate. The catalytic formulation includes a) a support material made of an aluminum oxyhydroxide or aluminum oxide within a weight ratio between 30 and 90%; b) a carbonaceous material in a weight ratio between 1 and 60%; c) a polymeric material soluble in water or in slightly acid solutions with the presence of oxydrile groups, within a weight ratio between 1 and 45%; d) a salt promoting the presence of phosphate ions within a weight ratio between 1 and 30%; e) an aqueous acid agglutination agent at a weight ratio between 1 and 15% and f) an alkaline metal halogen within a weight ratio between 1 and 80%.

(11) In one embodiment, the polymeric material is selected from the group consisting of poly(vinyl alcohol), chitosan, polyacrylamide, polyacrylates, and combinations thereof.

(12) In one embodiment, the phosphate salt is selected from the group consisting of dihydrogen phosphate, monoacid phosphate, sodium phosphate, potassium phosphate, and combinations thereof.

(13) In one embodiment, the acid agglutination agent is selected from the group consisting of aqueous solutions of formic acid, acetic acid a nitric acid, and mixtures thereof.

(14) In one embodiment, the alkaline metal halogen comprises potassium iodide.

(15) What follows is the detailed description of the general synthesis procedure of the catalysts. Each batch of catalytic material was synthesized to obtain, approximately, 200 g through a mixing procedure consisting of the following stages: 1) Each component is weighed according to the desired composition in each batch. 2) In an extended recipient, the main ingredients KI, Ca and Catapal B® are mixed using a nitric acid solution at 5 vol. %. 3) The mixture is homogenized. It is convenient to use the minimal amount of acid in order to get the convenient consistency for the extrusion-spheronization stage. The extrusion-spheronization stage presents diverse parameters, however, in this experimentation most of them were kept constant. Only the spinning rate of the base that shapes the spheres was varied as a function of the consistency (viscosity) of the cylindrical extrudate. 4) The calcination of the materials was carried out according to the following thermal program: 4.1. The material is submitted to heating from ambient temperature up to 130° C. with a heating rate of 5° C./min, keeping it for 2 h. 4.2. Afterward, it is increased from 130° C. to 450° C. at the same rate for 3 h. 4.3. The cooling process starts from 450° C. to 130° C., and it is kept at this point for 2 h and finally from 130° C. to ambient temperature.

Example 1

Synthesis of the Potassium-Iodide-Based Catalyst

(16) The first stage in the preparation of this catalyst consists in the dissolution of 15 g of poly(vinyl alcohol) in 300 mL of water at 90° C. with constant stirring. When it gets cold, a solution consisting of 92 g of KI and 60 mL of water is added and stirred until complete homogenization.

(17) Afterward, such solution is evaporated in a stove at 50-60° C. The obtained solid is ground and sieved.

(18) The other employed components are: 10 g of NaH.sub.2PO.sub.4, 12 g of activated carbon, 114 g of Catapal B® and HNO.sub.3 at 5% v/v was used as wetting agent.

(19) The integration method of the materials consists in mixing, gradually, the different solids by adding the necessary amount of nitric acid until forming a homogeneous paste. The percent composition of the solid catalyst on wet and dry basis (at its final stage) is shown in Table 1.

(20) TABLE-US-00001 TABLE 1 Catalyst composition on wet (recently prepared) and dry (after thermal treatments) bases. Composition on wet Composition on dry Component basis, wt. % basis, wt. % PVA 6 0 CA 5 5.2 NaH.sub.2PO.sub.4 4 4.8 KI 38 40 Catapal 47 50

(21) In order to shape the catalyst as a sphere, an extrusion/spheronization process was implemented. Once the spheres were obtained, they were dried under ambient conditions for 2 h and finally they were calcined with the characteristics described in Table 2.

(22) TABLE-US-00002 TABLE 2 Calcination stages Intervals Temperature Time (h) T.sub.AMBIENT-130° C..sup.  130° C. 2 130° C.-450° C. 450° C. 3 450° C.-130° C. 130° C. 2 .sup. 130° C.-T.sub.AMBIENT — —

(23) The catalytic material obtained with this procedure was ready to be evaluated in the CO.sub.2 cycloaddition reaction with propylene oxide. The reaction conditions were: temperature=160° C., pressure=29.5 kg/cm.sup.2 of CO.sub.2, 20 g of propylene oxide, reaction time=100 min, stirring=100 rpm, catalyst mass=1 g in a batch reactor. The following values regarding propylene cyclic carbonate were obtained: yield=93.3% and selectivity=98.75%.

Example 2

(24) The catalytic material used in this example features the same components and follows the same methodology described in Example 1, except for the absence of NaH.sub.2PO.sub.4. The reaction was performed under the same conditions of Example 1 and the obtained results were: yield=89.3% and selectivity=98.96%.

Example 3

(25) In this example a catalyst similar to the one in Example 1 was synthesized, but without poly(vinyl alcohol). The reaction results using this catalytic material were: yield=88.61% and selectivity=96.83%.

Example 4

(26) In this case, the catalytic material was prepared with a calcination methodology similar to the one shown in Table 2, with the difference that the maximal reached temperature was 550° C. The reaction results were: yield=69.3% and selectivity=86.60%.

Example 5

(27) In this example, changes were carried out regarding the phosphorus compound: one concerning the phosphate incorporation methodology and other with respect to its weight proportion in the catalyst. The catalytic spheres were obtained similarly to the procedure described in Example 1. At the initial preparation stage of the catalyst, phosphate was not added, which was included afterward by means of an incipient wetness process (when the spheres were formed). The employed amount was of 0.2 g in 10 mL of water. Finally, the obtained spheres were thermally treated at 210° C. for 4 h.

(28) The synthesis reaction for producing propylene carbonate using these materials gave a yield of 53.9% and selectivity of 98.15%.

Example 6

(29) This example features a modification of Example 5, which consisted of incorporating sodium dihydrogen phosphate from a higher concentration solution. The synthesis of the catalytic materials was carried out with the same methodology described in Example 5, where the modification consisted in impregnating the phosphate salt by dissolving 2 g in 10 mL of water in order to increase the salt concentration and its proportion on the surface of the spherical catalyst. The results of the cycloaddition reaction employing these catalytic materials were: yield: 56.8% and selectivity: 98.74%.

Example 7

(30) This example describes the composition of a catalyst that is similar to the one in Example 1, but without using poly(vinyl alcohol). The rest of the components were added like in Example 1 and the preparation procedures are the same as those described in Example 1. The cyclic carbonate reaction had a yield of 92.4% and a selectivity of 99.11%.

Example 8

(31) This example shows the preparation and evaluation performed with a catalyst having higher concentration of active phase, potassium iodide, and its percent composition was the following: 50% of KI, 6% of AC, 34% of Catapal B® and 10% of NaH.sub.2PO.sub.4, and a HNO.sub.3 solution (100 mL) at 5% was used as peptizing agent. The preparation, formation and calcination stages were the same as those described in Example 1. The results of the propylene cyclic carbonate reaction were: yield=96.6% and selectivity=98.24%.

Example 9

(32) This example presents the evaluation of a catalyst containing lower concentration of active phase, potassium iodide, and its percent composition was the following: 10% of KI, 6% of AC, 74% of Catapal B®, 10% of NaH.sub.2PO.sub.4 and a HNO.sub.3 solution (50 mL) at 5% was used as peptizing agent. The preparation, formation and calcination stages are the same as those described in Example 1. The results of the propylene cyclic carbonate reaction were the following: yield=68.36 and selectivity=99.01%.

Example 10

(33) This example features the evaluation of a catalyst having lower concentration of the active phase, potassium iodide, and its percent composition was the following: 10% of KI, 6% of AC, 74% of Catapal B®, 10% of NaH.sub.2PO.sub.4 and a HNO.sub.3 solution (100 mL) at 5% was used as peptizing agent. In this case, concentrated H.sub.3PO.sub.4 (3 wt. %) was added by the incipient wetness method. The preparation, formation and calcination stages are the same as those stated in Example 1. The results of the propylene cyclic carbonate reaction were the following: yield=70.31 and selectivity=88.45%.