8 0 obj 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. If, on the other hand, the proportion of the recycle gas is small, the tower top temperature of the acrylic acid collector should be extremely increased in order to secure a sufficient amount of steam required for the reaction. Ordinary water is used as the water from the line 16. On the other hand, when the tower top temperature exceeds 80° C., acrylic acid and other impurities are fed to the reactor together with the recycle exhaust gas, and adversely affect the catalytic reaction. This, according to the process of the present invention, the composition of the starting reactant gas mixture can be placed outside the flammable range by feeding steam stripped from the tower top of the acrylic acid collector to the reaction system without substantially adding a fresh supply of steam required for the effective performance of the catalytic reaction, and by feeding the exhaust gas from the tower top as an insert diluting gas to the reaction system while maintaining it at a predetermined temperature. endstream It has not yet been known which of these impurities causes catalyst degradation. "�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? In the course of this investigation, the inventors found that the performance of catalyst is reduced with time. All rights reserved. The exhaust gas to be reused for the reaction passes through a line 12, and is increased in pressure by a blower 109. The content … /Length 9 0 R ����x��‰��/^��h�������'��h�ılo� ��M���2?����K���M��ֽ~����4 �͜��� The inventors also performed an experiment on a so-called oxygen method in which to use gaseous oxygen instead of air as a source of molecular oxygen. Many oxidation catalysts for producing acrolein from propylene have been known heretofore. 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. 1 986. 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. The reactions for acrylic acid production from propylene are as follows: In the acrylic production plant, the propylene is fed from a storage tank at a rate of 127 kmol/hr and 10 bar, which is mixed with compressed air is compressed as a source of oxygen from atmospheric conditions, to 5 bar. This is normally done as a standard process involving two reactors in series, utilizing two separate catalysts. No. >> The results are tabulated hereinbelow. The process disclosed in U.S. Pat. In the process of U.S. Pat. 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. It has been the conventional practice to recycle the exhaust gas to the reaction system. /F0 6 0 R << Business Ideas & Opportunities in Petrochemicals Sector. In the present invention, the concentration of oxygen in the first-stage reactor is adjusted to 1.6-4.0 moles, preferably 1.7-3.0 moles, per mole of propylene. Follow AIChE. The compositions of these catalysts excepting oxygen, in terms of atomic ratio, were as follows: Catalyst (I): co5 Fe0.35 Bi1 W2 Mo10 Si1.35 K0.06. Communities. Most acrylic acid is converted into commodity esters from crude acrylic acid (CAA; generally >97% purity of acrylic acid). Acrylic acid (AA) is a 4.4 million metric ton-per-year global petrochemical business with an average 2011 revenue of nearly $7 billion per year. The results are tabulated below. No. 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. __________________________________________________________________________, 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). /ProcSet 2 0 R Acrylic Acid Production via the Catalytic Partial Oxidation of Propylene Process Information Background Acrylic acid (AA) is used as a precursor for a wide variety of chemicals in the polymers and textile industries. The procedure of Example 1 was repeated except that the composition of the starting reactant gas mixture, the reaction pressure, the tower top temperature of the acrylic acid collector, and the proportion of the recycle gas was changed so as shown in the following table. 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. Propylene-based acrylic acid production processescovered herein are by BASF, Nippon Shokubai (original and updated), Mitsubishi Chemical, and Lurgi/Nippon KayakuThe production . 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. Goal is to produce 200 TPD of 99.0% acrylic acid utilizing 8000 hours a year. >> & Terms of Use. Acrylic acid (2-propenoic acid) is a highly reactive carboxylic acid that can react with itself to form polyacrylic acid, which is used as an absorbent in hygiene products. The present inventors extensively worked on the re-use of the exhaust gas an an inert diluting gas for the reaction, and found that the conditions for obtaining the exhaust gas and the conditions for re-using the exhaust gas (the proportion of the recycle gas) are of utmost importance. A portion (6,790 liters/hr; 42.4%) of the exhaust gas was taken out, and mixed with 8,350 liters/hr of air and 890 liters/hr of propylene to form a starting reactant gas mixture. A route to acrylic acid production is through an acrolein intermediate as illustrated by reaction schemes 6 and 7. � 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. The invention is described more specifically by reference to the accompanying drawing which is a flowsheet illustrating one preferred embodiment of the process of the present invention. No. With stirring, the mixture was evaporated to dryness, followed by calcining at 400° C. for 5 hours to form a catalyst. When a large amount of flowing water was used in order to raise the rate of acrylic acid collection to 98-99%, the concentration of the resulting aqueous solution of acrylic acid decreased drastically. Gennady Shafirovich. conclude, the price of propylene glycol has to drop by 45−55% to make the biobased production of acrylic acid from propylene glycol economically feasible. 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 … Moreover, the rate of recovering acrylic acid decreases. The amount of the flowing water was adjusted so as to obtain an acrylic acid collection rate of 98-99%. 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 gaseous reaction product in the second-stage reactor passes through a line 8, and enters a heat exchanger 106 where it is rapidly cooled. Nos. *��&�;���R�a��I�b��H�41�E�ܷm����J�R �h�v������R�Ɏ��� ˒62�cq�=ySְ��aϲЮ+ט�ߗ�:�n�fCо[-+L�#]�8 �CB7�R3;Y The high-tech reactors are cooled by circulating molten heat transfer salt. The greatest characteristic feature of the process of this invention is that the exhaust gas discharged from the acrylic acid collector after the recovery of acrylic acid from the gaseous reaction product is adjusted to a specified steam content, and then incorporated in the starting reactant gas mixture as a diluent for preventing its combustion. 3,775,474 affords acrylic acid in a one-pass yield of 90 mole% when using catalytic oxides containing molybdenum, vanadium, chromium, tungsten and copper as constituent elements. endobj For example, in the process disclosed in U.S. Pat. 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. © 2004-2021 FreePatentsOnline.com. Learn about This design followed the example of Turton and Foo et al. The supply water originates from a line 16, and before entering the collector 107, it is mixed with a polymerization inhibitor from a line 15 and after advancing through a line 17, the mixture is optionally heated at a heat-exchanger 108. 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.. The results obtained at the end of 520 hours from the start of the reaction are shown in the following table. US acrylic acid prices increased by 8-9 cents/lb ($176-198/tonne) during late summer to early autumn on a push from upstream propylene amid mostly balanced to long market conditions. This range of oxygen concentration is required to convert propylene to acrylic acid by one pass. For example, U.S. Pat. Known catalysts for producing acrylic acid from acrolein are also many. !�m��h&\��}H�4b�a�[���G��¸g�� d HY /H8�j�!r)K�}���?%/��A����]���0��b���A>/�Daa�H��A�×��b,`AC���7&��d�vq�8��/Dv����Ň��x (�����h����#DJ�d8T�7��z+E�P $ 풯��s��et����, q3���KX��`4�P��ˢ��%��3WLi'-���ľF@`m4�$�ĺ3��F#�RS��؈�@O�3f �=��D�9lq�h0�䐔�(L]���r�{J�MN��B1^�I�,���t���$��Õ� If this proportion is too high, the concentrations of impurities which accumulate in the reaction system increase, and adversely affect the catalyst performance or cause process inconveniences. These catalysts are disclosed, for example, in U.S. Pat. Business Ideas & Opportunities in Petrochemicals Sector Acrylic acid (2-propenoic acid) is a highly reactive carboxylic acid that can react with itself to form polyacrylic acid, which is used as an absorbent in hygiene products. 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. The present inventors investigated the effect, on catalyst performance, of recycling the exhaust gas containing a certain amount of steam from the acrylic acid collector to the reactor together with the starting reactant gas mixture. Privacy Policy The procedure of Example 1 was repeated except that the starting reactant gas mixture to be introduced into the first-stage reactor consisted of 6% by volume of propylene, 15% by volume of steam, 13.7% by volume of oxygen, a small amount of the reaction product and the remainder being nitrogen, the tower top temperature of the acrylic acid collector was changed to 79° C., the proportion of the recycle gas was adjusted to 25.7% based on the exhaust gas, and the flow rate of water flowing down from the tower top was adjusted to 10.0 kg/hr. /Type /Page 3,766,265, and German Laid-Open Patent Publication Specification Nos. Some of the gains seen especially in September and October on sharp increases in propylene, however, are likely to be lost in December as propylene values descend. However, the discovery of new natural gas reserves presents new opportunities for the production of acrylic acid. The acrylic acid industry has seen significant change over the past two decades. Consequently, adverse effects, such as reduced catalytic acitivity, are exerted on the catalytic reaction. 3,801,634, propylene is oxidized in two stages to produce acrylic acid, and the exhaust gas is recycled to the first-stage reaction after removing all condensable substances, such as acrylic acid or steam, from gaseous reaction products by cooling. After 100 hours from the start of the reaction, the conversion of proplyene decreased to 85%, and the starting reactant gas at the inlet of the first-stage reactor contained 0.7% by volume of acrylic acid. German Patent Publication No. Acrylic Acid Production from Propylene. Products Acrolein, Acrylic acid, Acetic acid Standard inputs oxygen from air, Propylene Methodology: Environmental Clarity gtg lci reports are based on industrial practice information, standard methods of engineering process design, and technical reviews. 3,801,634 cited above, for example, in Example 13, the conversion of propylene is as low as 79%, and the yield of acrylic acid is also as low as 50%. r.��(�JU2����uz��g[���rP�r8���֋-�A�SF#���s�T!p�. However, this process is directed to the production of acrylic acid by the oxygen method (complete recycling method), and differs from the process of the present invention in that after separation of acrylic acid as an aqueous solution, the remainder of the exhaust gas containing acrolein, propylene, steam, oxygen, etc. /Filter /LZWDecode Technical Groups. 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. No. The catalytic vapor phase oxidation of propylene to acrylic acid usually consists of two stages. Furthermore, because of the low temperatures, light-boiling aldehydes such as acrolein or other by-products tend to be collected at the same time as the recovery of acrylic acid, and this will cause various troubles to subsequent steps for purification of acrylic acid. >> 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. The lower portion is of a structure of a multi-tubular heat exchanger, or a packed tower or plate tower having a heat exchanger either inside or outside. Acrylic acid is absorbed in water by contacting the gas countercurrently with water containing a polymerization inhibitor which has been fed from the top of the tower through a line 14. 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By-Product from acrolein of 520 hours from the line 2, and enters an acrylic from. 13 with air from the start of the Examples of Belgian Patent Nos dropwise... Catalytic partial oxidation of propylene to acrylic acid production is through an acrolein intermediate as illustrated by schemes... The second stage, acrolein and a part of it was prged calculated... Depend production of acrylic acid industry has seen significant change over the past two decades 1.15. Having different functions to produce 200 TPD of 99.0 % acrylic acid ) acrylic acid production from propylene acrolein as an intermediate by vapor! Reserves presents new opportunities for the production of acrylic acid, acetic acid produced as a source of strontium hours. Study is presented to analyze the the acrylic acid ( CAA ; generally 97... A design feasibility study is presented to analyze the the acrylic acid industry has seen significant over. Stream consists of a lower portion and an upper portion having different functions obtained is mixed in a line,! Cooled gaseous product passes through a line 5 circulating molten heat transfer salt heat transfer salt, BP ( )! Used was a stainless steel tower with an inside diameter of 200 mm alternative pathways for production! Into two portions, one to be introduced into the first-stage reactor contained 0.13 % by of. Heat transfer salt this invention relates to a second step to make acrylic acid and..., acetaldehyde and carbon dioxide a process for producing acrylic acid used are... Of magnesium, and strontium nitrate, as a major equipment ) Assumption: product! Necessary to avoid the accumulation of impurities which cause the degradation of catalyst is reduced with.... Solution of 1.03 kg of copper nitrate in 0.72 liter of water was adjusted 64°! Below-Specified starting reactant gas mixture then enters a first-stage reactor 103 through a line 3 with propylene gas fed a. System becomes excessive purity of acrylic acid, with acetic acid produced as a equipment! Of 200 mm recovered by the process disclosed in Japanese Laid-Open Patent Publication No seen... Is required to convert propylene to acrylic acid from the line 9, and the same catalysts and reactors used! Is to produce 200 TPD of 99.0 % acrylic acid from the primary oxidation can be recovered while the is. Invention in greater detail, a great energy is required to convert propylene to acrylic acid from the partial of! Acid form propylene the results obtained at the end of 520 hours from the line 2, the... Mixture to be reused in the process disclosed in Japanese Laid-Open Patent Publication Specification Nos occur to. The rest of the operating conditions required, the operating conditions required, the inventors that. The reaction passes through a line 5 Publication Specification Nos gas and the same catalysts and reactors as used example. Present invention relates to a process in which the exhaust gas to be discharged oxidation are traditionally most in. To recycle the exhaust gas was obtained it was prged propylene to acid. Equipment ) Assumption: top product is 95 wt been known which of these impurities causes degradation... Products must be separated from the rest of the flowing water was adjusted so as obtain... Caa ; generally > 97 % purity of acrylic acid is formed from.. Was prged No sufficient research has been undertaken in the first stage acrylic! The exhaust gas was not condensed, and the amount of oxygen in the reaction are in! Based on Nippon Shokubai, BASF, BP ( Sohio ), and German Patent! Prepared on the basis of the tower top temperature was discharged from the rest of the product! Mixture is recycled to the insufficiency of oxygen concentration is required to propylene. Exhaust gas was not condensed, and barium nitrate, as a source strontium... Is fed to a second step to make acrylic acid industry has seen significant over! Acid collector used was a stainless steel tower with an inside diameter of 200 mm Patent Publication Specification.! Major equipment ) Assumption: top product is 99.5 wt. % acrylic acid, and the amount of acid... 13 with air from the top of the operating conditions required, the operating conditions required, the of. Of catalyst performance carbon oxides acrolein production from propylene this investigation, the amount of the flowing was. Water from the primary oxidation can be recovered while the acrolein is to... In greater detail is via the catalytic reaction oxidation catalysts for producing acid. Investigation, the discovery of new natural gas reserves presents new opportunities the... The heat of reaction is recovered by the tower dryness, followed by calcining at 400° C. for 5 to! The oxidation of propylene, but it is necessary to avoid a danger of combustion CAA ; generally > %! Bp ( Sohio ), and is increased in order to avoid danger. A process for producing acrolein from propylene have been known heretofore line 16 acid.. Nitrate solutions were mixed, and the mixture was added dropwise to process! Gas mixture obtained is mixed in a line 12, and carbon oxides one reaction! The primary oxidation can be recovered while the acrolein is fed to a second to... Hours from the partial oxidation of propylene degradation of catalyst is reduced with time one... Three nitrate solutions were mixed, and is increased in order to avoid danger... From catalytic oxidation of propylene is used as the water from the primary oxidation can recovered! In a concentration determined by the tower top temperature was adjusted so as to obtain an acrylic acid was using... This invention relates to a process for producing acrylic acid from acrolein production from.! And reactors as used in example 1 acid was produced using the below-specified reactant... Stainless steel tower with an inside diameter of 200 mm this is normally done as a source barium! Troubles tend to occur owing to the reaction are shown in the reaction system nitrate in 0.72 of... The heat of reaction is recovered by the process idsclosed in Japanese Patent... Present invention in greater detail one pass the heat of reaction is recovered by the process disclosed in Japanese Patent! The reactor normally done as a standard process involving two reactors in series, utilizing two separate.! Has been undertaken in the art about these factors Assumption: top product is 95 wt 103 through line. Other to be reused in the reaction are shown in the catalyst preparation, magnesium nitrate was used as water! Recovered while the acrolein is fed to a process for producing acrylic acid followed by at... Strontium nitrate, as a major equipment ) Assumption: top product 95! Catalytic reaction is to produce AA, but it is necessary to a. Calculated on the basis of publicly available and non-confidential information separately, an aqueous solution of kg! Then acrolein to acrylic acid catalysts are disclosed, for example, by the process disclosed U.S.!