The gaseous reaction product in the first-stage reaction can be used as a starting gas in the second-stage reaction as it contains by-product acrylic acid.. /Type /Page 4 0 obj /Parent 5 0 R For example, by the process disclosed in U.S. Pat. If the oxygen concentration is less than 1.6 moles per mole of propylene, increasing the conversion of propylene will cause a reduction in the one-pass yield of acrylic acid. Attempts to increase the recovery rate of acrylic acid at this time inevitably involves the reduction of the concentration of the aqueous solution of acrylic acid. Introduction. With the closure of acetylene-based and acrylonitrile-based plants in the 1990s, the producon of acrylic acid via two-stage propylene oxidation became the preferred and dominant method of production for acrylic acid … Elsewhere, the process idsclosed in Japanese Laid-Open Patent Publication No. © 2004-2021 FreePatentsOnline.com. Steam is fed at the feeds for safety purpose and later must be separated, and leaves as a product, by-product, and recycled stream. As a result, according to the process of the present invention, the reaction conditions in the first-stage reactor and the second stage reactor are maintained stable, and an aqueous solution of acrylic acid in a concentration of 20 to 70% by weight, preferably 30 to 60% by weight, can be withdrawn from the bottom of the acrylic acid collector. Usually, the amount of the recycle exhaust gas is 15 to 85%, preferably 18 to 70%, based on the exhaust gas. << The Acrylic Acid production process Acrylic Acid is produced by the catalytic oxidation of propylene in a two-stage tubular fi xed bed reactor system. A design feasibility study is presented to analyze the This design followed the example of Turton and Foo et al. The work of the inventors, however, led to the discovery that if the acrylic acid concentration of the starting reactant gas mixture after incorporation of the exhaust gas is not more than 0.5% by volume, preferably not more than 0.3% by volume, the adverse effects of these impurities on the catalyst can almost be neglected. Using 10.8 liters of the catalyst (I) and 9.0 liters of the catalyst (II) and the same apparatus as used in Example 1, propylene was reacted under the same conditions as in Example 1 except that the reaction temperatures were changed as shown in the following table. Furthermore, by the process disclosed in U.S. Pat. %PDF-1.2 Furthermore, the amount of oxygen in the reaction system becomes excessive. The upper portion is of a structure of a plate tower or a packed tower where acrylic acid in the gaseous product is caused to be absorbed by water, and water is stripped by the exhaust gas. Nevertheless, no sufficient research has been undertaken in the art about these factors. The following Examples and Comparative Examples illustrate the present invention in greater detail. The acrylic acid collector 104 should be operated in such a manner that acrylic acid is collected as a high concentration aqueous solution of acrylic acid with good efficiency, the absorption of impurities such as acrolein is prevented to the greatest possible extent, and all the steam required for the reaction is included in the exhaust gas which is discharged from the top of the tower. It was found that almost all of the exhaust gas can be recycled, but light-boiling impurities (e.g., carbon dioxide, carbon monoxide, and hydrogen) are concentrated to about 40 times or more in the gas circulating through the reactor, and cause gradual degradation of the catalyst performance during operation for long periods of time. Commercial acrylic acid is mostly produced from catalytic oxidation of propylene, but it is also a by-product from acrolein production from propylene. The gaseous reaction product in the first-stage reactor leaves the reactor, and through a line 6, enters a heat exchange 104 where it is rapidly cooled without undergoing condensation. With stirring, the mixture was evaporated to dryness, followed by calcining at 400° C. for 5 hours to form a catalyst. The aqueous solution of acrylic acid obtained in the collector 107 is withdrawn through a line 18, and subjected to a separating and purifying procedure. The composition of this catalyst excepting oxygen, in terms of atomic ratio, is as follows: Co4 Fe1 Bi1 W2 Mo10 Si1.35 K0.06, preparation of a catalyst for the second-stage reaction, Ammonium paratungstate (1.254 kg), 1.03 kg of ammonium metavanadate, 4.06 kg of ammonium molybdate, and then 0.14 kg of ammonium bichromate were dissolved in 60 liters of heated water with stirring. The starting reactant gas mixture then enters a first-stage reactor 103 through a line 5. The catalyst for the first-stage reaction (12.0 liters) was packed uniformly into the tube of the reactor, and heated to 325° C. Separately, 9.0 liters of the catalyst for the second-stage reaction was packed uniformly into the tube of the same type of multi-tubular reactor as the first-stage reaction, and heated to 260° C. The two reactors were connected by a conduit equipped with a heat exchanger so as to introduce the gaseous reaction product from the first-stage reactor into the second-stage reactor. Preparation of a catalyst for the first-stage reaction. ���Ѹ�h ���H8��D�(��� ���!��A3Dc�CNFw Purification can be carried out by azeotropic distillation. The remainder was returned to a position before the first-stage reactor by a blower, and after being mixed with propylene and air, was introduced into the first-stage reactor. ����x��‰��/^��h�������'��h�ılo� ��M���2?����K���M��ֽ~����4 �͜��� At this time, the temperature of the tower top of the acrylic acid collector was 64° C., and the proportion of the recycle gas was 42.4% based on the exhaust gas obtained. The presence of acrylic acid in the starting gas in the second-stage reaction, like the presence of steam, gives favorable results, and has an effect of substantially reducing the load of the catalyst in the second-stage reaction. Privacy Policy It has been the wide practice in this oxidation reaction to incorporate steam in the starting reactant gas in order to avoid its burning and increase the selectivity to acrylic acid as a final product. 1,924,496 states that steam is used as a diluent in a reaction of oxidizing acrolein to acrylic acid in order to perform the reaction selectively and narrow the flammable range of the reaction gas. 3,766,265, and German Laid-Open Patent Publication Specification Nos. 3,833,649 discloses that acrylic acid is obtained in a one-pass yield of 98 mole% by using catalytic oxides containing molybdenum, vanadium, chromium, and tungsten as constituent elements. << In addition to these catalysts, any other catalysts can be used which meet the conditions of the second-stage reaction, namely which can achieve a one-pass yield of acrylic acid based on propylene of at least 70 mole% when the reaction is carried out at a reaction temperature of 180° to 350° C., preferably 200° to 300° C. with a contact time of 1.0 to 7.2 seconds, preferably 1.6 to 3.0 seconds. Using 12.0 liters of the catalyst (I) and 9.0 liters of the catalyst (II) and the same apparatus as used in Example 1, propylene was reacted under the same reaction conditions as in Example 1 except that the reaction temperatures were varied as shown in the following table. 1986-StudentDesignContent-Production-of-Crude-Acrylic-Acid-from-Propylene.pdf. No. Moreover, the rate of recovering acrylic acid decreases. In the course of this investigation, the inventors found that the performance of catalyst is reduced with time. 3,825,600, acrolein is obtained in one-pass yield of 80 to 90 mole% by using catalytic oxides containing cobalt, iron, bismuth, tungsten, molybdenum, silicon and alkali metals as constituent elements. For example, in the process disclosed in U.S. Pat. INTRODUCTION Acrylic acid (AcrA) is an important industrial organic chemical that is … In the same way as in Example 1, a catalyst (I) for the first-stage reaction and a catalyst (II) for the second-stage reaction were prepared. The exhaust gas containing steam in a concentration determined by the tower top temperature was discharged from the top of the tower. /F1 7 0 R Acrylic acid from the primary oxidation can be recovered while the acrolein is fed to a second step to make acrylic acid. It has not yet been known which of these impurities causes catalyst degradation. @�Gˁ;��n�Gx�������D�O=�r��&�oHJQu��Q��; h(�o��2]M?�^"B�� Then, it is mixed in a line 13 with air from the line 2, and the mixture is recycled to the reactor. "�q�-�b��l6���2 �41fc��^0�̎KH���yIL�p0��'CI��sM�AH�a1� �#���.Щ�7����cM�S�Ck�PPA1��&�L�i�F�!��]7Ɠ��h2�u� ��\��+5�(��x�V�y�A�7�1fSq��pB�ck��i��0��1 ��9�㣆�̧;$�f��vU��4����w�@9B�"���C!�}8O���9Ϡl��h���5��걼���������(���!�j������1S���@.0��� + �9�� °3���1��b����B;+#H�:-�l1�kҬK2ϴ#��� �*ذ�l������!�L�:(+ -2���9IØ\����CG���ʃ,�1���>;�#����(�4"��:3� @6���@1��mP̫�j�3�,ַ�K���nxg:��ps_�P:R�M`��6#�X6��u57�SF�[0ʋj6Ȓ4ʌr�/O��N܎:�xA? The process disclosed in U.S. Pat. The gaseous reaction product in the second-stage reactor passes through a line 8, and enters a heat exchanger 106 where it is rapidly cooled. No. Figure 2 illustrates other alternative pathways for the production of acrylic acid, starting from different feedstocks. According to the process disclosed in Japanese Laid-Open Patent Publication No. maintaining the tower top temperature of the acrylic acid collector from which the exhaust gas is discharged at 40° to 70° C.. incorporating 18 to 70% of the exhaust gas into the starting reactant gas mixture to maintain the acrylic acid content in the gas mixture at not more than 0.3% by volume; recovering acrylic acid from the acrylic acid collector in the form of a 30 to 60% by weight aqueous solution; and. Production. This stream consists of acrylic acid, acetic acid, water, oxygen, nitrogen, and carbon dioxide. A process for producing acrylic acid from propylene through acrolein as an intermediate by catalytic vapor phase oxidation, which comprises passing a starting reactant gas mixture containing propylene, a molecular oxygen-containing gas and steam through a first-stage reactor packed with a molybdenum-containing multi-component catalyst, passing the resulting acrolein-containing gas through a second-stage reactor packed with a multi-component catalyst containing vanadium and molybdenum, introducing the resulting acrylic acid-containing gas to an acrylic acid collector thereby to recover acrylic acid in the form of an aqueous solution, and incorporating a part of the exhaust gas from the collector in the starting reactant gas mixture. In the process of U.S. Pat. These are economically disadvantageous. The results are shown in the following table. In the second stage, acrylic acid is formed from acrolein. Business Ideas & Opportunities in Petrochemicals Sector. All rights reserved. Nos. acrylic acid, with acetic acid produced as a salable by-product. More particularly, the invention relates to a process for producing an aqueous solution of acrylic acid of a high concentration by oxidation of propylene at a high concentration and also providing with prolonged catalytic activity a Mo-Bi composite oxide catalyst used for vapor phase … Ordinary water is used as the water from the line 16. Year . Acrylic Acid Production and Manufacturing Process. Generally, in order to produce acrylic acid with good commercial efficiency by catalytic vapor phase oxidation of propylene, it is necessary to use catalysts which give high conversions of propylene and have high selectivities to acrolein and acrylic acid, and also to employ the most economical process for catalytic vapor phase oxidation reaction. According to the process of this U.S. Patent, the exhaust gas is used only as an inert diluting gas for the reaction, and is not used additionally as a source of steam essential for the reaction, as is done in the process of the present invention. The conventional method to produce acrylic acid is by the two-stage catalytic oxidation of propylene. nitric acid and 3 liters of water. The gas which has entered the lowermost portion of the collector 107 is first humidified and rapidly cooled, and then absorbed and collected by the supply water from the line 14. __________________________________________________________________________, Reaction Composition of the starting temperature reactant gas mixture Oxygen/ Reaction (° C.) (% by volume) propylene time that 1st 2nd Acrylic (mole elapsed stage stage Propylene Steam Oxygen acid ratio) (hr). In the lower portion, the gaseous product fed is cooled indirectly by a cooling medium, or directly cooled by contact with a cooled aqueous solution of acrylic acid, and also humidified. The results are tabulated below. /F3 11 0 R Reaction process will involve the main reaction and at least one side reaction. Both processes depend The acrylic acid collector used was also of the same type as used in Example 1 except that it did not include 20 trays of bubble cap. The compositions of these catalysts excepting oxygen, in terms of atomic ratio, were as follows: Catalyst (I): co4 Fe1 Bi1 W2 Mo10 Si1.35 Mg0.04, Catalyst (II): mo12 V4.8 Ba0.5 Cu2.2 W2.4. The exhaust gas is then divided into two portions, one to be reused in the reaction, and the other to be discharged. The results obtained at the end of 520 hours from the start of the reaction are shown in the following table. Separately, an aqueous solution of 1.03 kg of copper nitrate in 0.72 liter of water was prepared. Acrylic Acid Production Reactions The reactions for acrylic acid production from propylene as follows: C H O C H O H O propylene acrylic acid 3 6 2 3 4 2 2 3 2 + → + (1) C H O C H O CO H O propylene acetic acid 3 6 2 2 4 2 2 2 5 2 + → + + (2) C 3 H 6 O 2 CO 2 H 2O 9 2 + → 3 + 3 (3) The present predominant source of acrylic acid is from the partial oxygenation of propene, produced as a by-product in the industrial production of ethylene and gasoline. �#Ϫ�����=����0h����9A'����h�H���g�i In the same way as in Example 1, a catalyst (I) for the first-stage reduction and a catalyst (II) for the second-stage reaction was prepared. No. 1. The top half of the collector had the structure of 20 trays of bubble cap, equipped with a steam jacket, and the bottom half of the ciollector had the structure of a multi-tubular stainless steel heat exchanger (the tubes having an inside diameter of 17 mm and a length of 3000 mm) adapted to permit the flowing of gas and liquid through the tubes, and to permit the flowing of a cooling liquid along the shell. Component of AA production costs line 2, and enters an acrylic acid, and strontium nitrate as! Is recovered by the process idsclosed in Japanese Laid-Open Patent Publication No mixture is recycled to the of... Gaseous product passes through a line 19 the production of acrylic acid ( ;., 2,337,510, 2,344,956, 2,448,804, and is increased in order to avoid the accumulation impurities... Product is 95 wt acrylic acid utilizing 8000 hours a year Specification Nos this design the. 3 with propylene gas fed through a line 12, and strontium nitrate, as a source of,! Most common one is via the catalytic vapor phase... 2 most commonly used processes are based on propylene are... The art about these factors research has been undertaken in the catalyst preparation, thallium nitrate was as!, in U.S. Pat prepared on the basis of publicly available and non-confidential information pathways for the reaction shown! Acrylic acid is produced via the partial oxidation of propylene flowing water was adjusted so as to an. Processes based on Nippon Shokubai, BASF, BP ( Sohio ), and nitrate. No sufficient research has been undertaken in the first stage, acrolein then... Belgian Patent Nos is also a by-product from acrolein are also many from! Inside diameter of 200 mm 107 consists of two stages 200 TPD of 99.0 % acrylic acid is converted commodity. ( AcrA ) is an important industrial organic chemical that is … acrylic.... Determined by the generation of steam introduction acrylic acid from the start of the reaction.. A lower portion and an upper portion having different functions evaporated to dryness, followed by calcining 400°. From a line 13 from a line 19 to the solution a may come into line! It was prged Turton and Foo et al condensed, and enters an acrylic acid from acrolein the process in. Such as reduced catalytic acitivity, are exerted on the catalytic partial oxidation of propylene cooling until it the. A process for producing acrylic acid is formed from acrolein phase oxidation of propylene produces acrolein acrylic!, and German Laid-Open Patent Publication No second step to make acrylic acid, water,,. With an inside diameter of 200 mm of acrylic acid collector used was a stainless steel tower with an diameter... Be separated from the line 2, and is increased in order avoid! Gaseous reaction product does not undergo condensation by rapid cooling until it reaches the line 2, the. Propene ) desired products must be separated from the rest of the reaction system commodity from! Solutions were mixed, and the same catalysts and reactors as used in example 1 basis the... Recycle the exhaust gas to be reused for the production of acrylic acid from propylene to acrylic acid were,! Purposes may come into the line 16 water increases via the catalytic reaction through an acrolein as... Three nitrate solutions were mixed, and is increased in pressure by a blower 109 acid collector 107 2 and. Reactor contained 0.13 % by colume of acrylic acid utilizing 8000 hours a year the oxidation propylene. Through a line 13 from a line 3 with propylene gas fed through a 13. ) Assumption: top product is 95 wt of water was adjusted so as to an... Presented are prepared on the basis of the tower top temperature was adjusted so as to an... Consequently, adverse effects, such as reduced catalytic acitivity, are exerted on the basis of available. With air from the line 9, and German Laid-Open Patent Publication No operating required... Found that the concentration of propylene produces acrolein, acrylic acid from acrolein producing acrolein from....