MINDTHEGAPLorena Oviol, Manuel Bruns, Vladimir Fridman, Jay Merriam and Michael Urbancic, Süd-Chemie, a Clariant Group Company, take a look at the next generation in on purpose olefins production. T he rapid emergence of shale gas has fundamentally shifted the balance in the olefins markets. As natural gas prices drop with increasing supply, olefin cracker operators have shifted to lighter feed and are therefore producing lower levels of propylene and higher olefins. When added to new light cracker production from the Middle East, the gap between supply of C3, C4 and higher olefins compared to the growing demand of their derivatives continues to expand. These market trends have combined to create a flurry of interest in the so called ‘on purpose’ olefins production technologies. CLARIANT INTERNATIONAL LTD Rothausstrasse 61 CLARIANT INTERNATIONAL LTD 4132 Muttenz 61 Rothausstrasse Switzerland 4132 Muttenz Switzerland CATALYSIS & ENERGY [email protected] CATALYSIS & ENERGY [email protected] WWW.CATALYSIS-ENERGY.CLARIANT.COM WWW.CATALYSIS-ENERGY.CLARIANT.COM CLA Artikelrückseite 0812 f03.indd 1 CLA Artikelrückseite 0812 f03.indd 1 31.08.12 16:45 31.08.12 16:45 The previous generation catalyst. followed by regeneration of the catalyst for a similar period of time.1 Later. 3 The key principal of the process is that the consumption of heat during the endothermic dehydrogenation reaction is closely in balance with the heat restored to the bed during the reheat cycle. Propane conversion over Catofin PS catalyst with and without HGM at the same pilot plant conditions. These processes are designed to run adiabatically. was tested after 637 days on stream (DOS) of commercial operation in a propane dehydrogenation plant. Al)2O3 phase. The results from performance testing of spent catalysts confirm the improved performance (Table 1). the PS version still exhibits much greater conversion and selectivity compared to the previous catalyst. The experience gained through years of operation has been implemented to boost the catalyst performance. maximum use of exhaust streams for better energy savings and improved valve construction for even greater reliability. Under these harsh operating conditions. the reactor vessel cycles between the dehydrogenation step and the regeneration step. The data also shows that despite having a much longer on stream time.2. cyclic processes in which light paraffins are catalytically dehydrogenated to produce the corresponding olefins and Figure 1. ENGINEERING Reprinted from September 2012 . High activity. it was utilised for production of propylene by dehydrogenation of propane. Even after 50% longer service. Cyclic operation of a Catofin and Catadiene dehydrogenation reactor. Catalyst improvements The Catofin and Catadiene processes are fixed bed. Süd-Chemie has continued to improve the Catadiene and Catofin catalysts by working with its exclusive licensing partner. the latest generation catalyst had significantly less formation of α-(Cr. The recent improvements made to the Catofin and Catadiene catalysts and processes have helped to boost their competitiveness and reliability for dehydrogenation processes. Al)2O3. Since acquiring the Houdry processes more than 20 years ago. Houdry further developed and commercialised the process for one stage dehydrogenation of n-butane into butadiene in what is now known as the Catadiene® process. This experience has also applied to the scale up of this technology. The thermodynamics of dehydrogenation require operation at a relatively high temperature (600 – 650 ˚C). Lummus Technology. Multiple reactors are used to maintain a continuous product flow with a typical cycle length of 20 – 30 mins. isobutylene and butadiene. a CB&I business sector. In the 1990s. and compared to the next generation Catofin PS catalyst. Later. the first generation proprietary chromium oxide/alumina catalysts had a lifetime of only six months.4. The value of this ongoing development is reflected in the >98% on stream factor that is typical for operating units. with the catalyst on hydrocarbon feed for very short cycles (7 – 15 mins). in the 1980s. This process was initially used for production of butylenes during World War Two. high selectivity and long catalyst life are key performance demands for the cost effective production of propylene.6 – 9 This understanding led to the development of more stable catalysts in which the migration of chromium into the alumina lattice is inhibited. During operation. These processes are known as the Catofin® technologies. Currently the three largest propane HYDROCARBON Figure 2. and unit capacities of up to 850 000 metric tpy are now possible. Hot air flow and combustion of coke are two main sources of heat input to the bed. this technology was applied to the production of isobutylene for methyl tertiary butyl ether (MTBE) by dehydrogenation of isobutane. It was developed by Eugene Houdry in 1942 to remove hydrogen from paraffins with high conversion and selectivity. the primary cause of catalyst deactivation was shown to be the conversion of the active chromium oxide phase into an inactive solid solution of α-chromium oxide and α-aluminum oxide or α-(Cr. thus demanding a robust catalyst. Specific improvements made in recent years include: integrated equipment to optimise heat balance. The cyclic nature of these processes is illustrated graphically in Figure 1.The Houdry® process for olefin production is one of the earliest petrochemical technologies. isobutylene and butadiene production. which explains the higher observed activity and selectivity retention. Catofin STD. and to improve the design of major equipment to increase the unit reliability. hydrogen. Equipment reliability improvement The Catofin and Catadiene technologies have long operating histories for propylene. 5 After extensive study. The latest generation catalysts show high performance for periods spanning approximately 3 – 4 years. Jubail Industrial City. Upon loading in the catalyst bed. The first experiments to test the HGM concept in an adiabatic pilot plant were very encouraging. USA. (HGM). HGM does not change the intrinsic selectivity of the catalyst. This was mainly the result of air flow rate limitations due to pressure drop across the bed. After several years of investigation. which can cause byproduct formation. the metal oxide is reduced with the generation of heat (Equation 1). Propylene selectivity as a function of propane conversion over Catofin PS catalyst. Jubail Industrial City. Furthermore. Properties of catalyst samples taken from the same commercial plant show the improvement in stability of the latest generation catalyst Catofin STD Days on stream α-(Cr. During the regeneration stage of the cycle. Reprinted from September 2012 HYDROCARBON ENGINEERING . Operation at lower air temperature can reduce the deactivation rate of the catalyst and thus provide longer catalyst life. a dramatic increase in propylene selectivity was also observed with the use of HGM (Figure 3). These factors combine to promote an increase in total propylene selectivity and thus increase the yield of the Catofin process. Alternatively. HGM has direct contact with the catalyst. a novel approach to heat transfer to the bed had to be developed. reduction oxidation mode. and confirmed that addition of HGM to the catalyst bed allowed the same paraffin conversion to be achieved at significantly lower air inlet temperatures. This approach considerably reduces the heat limitations of the original process. HGM can provide an optimal conversion profile in the catalyst bed that minimises the retention time of the product olefin. USA. or much higher paraffin conversion at the same air temperature (Figure 2).10. and the short regeneration time.Al)2O3 [wt%] Propane conversion* 637 56 23% 80% Catofin PS 991 29 80% 100% Figure 4. and thereby improving the propylene selectivity. This enhances heat transfer efficiency and allows optimisation of the catalyst bed temperature profile for the subsequent endothermic dehydrogenation reaction. Extensive additional tests confirm that the application of this concept will allow: nn A significant increase of the olefin production rate by increasing the yield or by operation at higher liquid hourly space velocity (LHSV).. The HGM product consists of a metal oxide on a proprietary support that chemically generates heat in situ. restricting paraffin conversion and therefore the olefin production rate. 11 This material meets several key performance parameters. selectivity or lifetime of the catalyst.dehydrogenation units in commercial operation are using Catofin technology: nn Petrologistics. Enterprise Products Partners have recently announced that they will build a new 750 000 metric tpy Catofin unit on the Texas Gulf Coast. However. nn Advanced Petrochemical Company. Of course. Kingdom of Saudi Arabia. one that could take advantage of the fact that this process operates in a cyclic. To address this issue. Table 1. and shows no negative impact on the activity. the reduced metal is converted back to the oxide form providing an additional amount of heat (Equation 2): MeOx + H2 Me + H2O Me + O2 MeOx ΔH < 0 ΔH < 0 (1) (2) Next generation technology Heat input to the catalyst bed has been a critical limiting factor for these dehydrogenation processes. Kingdom of Saudi Arabia. HGM can give a significant boost in Propylene selectivity* *Relative to fresh base catalyst selectivity over catalyst systems without HGM. eliminating exposure of the product olefin to the higher temperatures. slated for start up in 2015. a new material was developed that is referred to as ‘heat generating material’ Figure 3. by proper design HGM can provide the optimum temperature profile in the dehydrogenation catalyst bed. with and without HGM. nn Saudi Polyolefins Co. Perhaps more interestingly. including the ability to produce heat while remaining inactive to the feed and products. Texas. During the reduction stage of the cycle. Vol. 'Endothermic hydrocarbon conversion process'.CLARIANT. HORNADAY. E. Advances in Petroleum Chemistry and Refining. (London).Z. nn Lower energy consumption by reducing the amount of air used during the regeneration part of the cycle without reducing the production rate. HORNADAY.J. 2.973..997 (1947). continuing the high performance of these catalysts.. 11. M. JASINSKI J. A.419. 1953. Inc. 5. US Patent No. E.029 (1947). V. V.. Note that the data for conversion and selectivity of the processes is compared at equivalent operating conditions using the same catalyst loading configuration and comparable severity. ROKICKI. Paris. 9.423. FRIDMAN. E..623 (2009). M. lower energy consumption. URBANCIC. E. MERRIAM. Commercial demonstration The actual performance of HGM compared to a non-HGM case in the first commercial operation is shown in Figure 4. nn Further reduction in the inlet hydrocarbon temperature to further increase olefin selectivity. 2001.Z. URBANCIC. 7. Proceedings of 19th North American Catalysis Society Meeting. ROMAINE-SCHMIDT. FRIDMAN.Z.CATALYSIS-ENERGY.Z. 'Reduction of the Al-Cr catalyst selectivity as a result of its deactivation'. V.nn A significant increase of the olefin selectivity and reduction of the monomer factor by optimising the catalyst bed temperature profile. US Patent 2. 7.. US Patent No. 2005. 4.J. FRIDMAN. Dhahran. Notes Houdry. V. 2011. 'Catalytically inactive heat generator and improved dehydrogenation process'.F. 1961. US Patent 2. 'A New Houdry Catalyst for the ‘Third wave’ . Conclusion Ongoing research and technical service efforts in the catalyst and process technology for Catofin and Catadiene have resulted in improved performance for propylene. Thus improved selectivity for the HGM case has been confirmed in commercial operations.Z. Interscience. 'Catalyst and process improvements for increased stability CATOFIN i-C4 and C3 dehydrogenation'.A. 'Stability of active sites precursors of Al-Cr dehydrogenation catalyst'. Catalysts in Petroleum Refining and Petrochemicals. A.. nn Increase catalyst life by minimising the air inlet temperature. HOUDRY.. B.COM HYDROCARBON ENGINEERING Reprinted from September 2012 . HOUDRY. G.622. V. 6. FERRELL F.F.207 (2011). 11 – 12. Proceeding of Saudi-Japanese Symposium. DAVIES. Vol... Catofin and Catadiene are registered trademarks of Süd-Chemie. the proprietary HGM. 2009. G.. J. M. S. Saudi Arabia. V. can significantly boost selectivity and 10. Petroleum Refiner. San Francisco. pp 451 – 488. Philadelphia. ROKICKI. References 1. BRUMMER. 8. 11th. Detroit. September (1953). N4. S50 (Aug 2010). The most recent technology breakthrough.Propane Dehydrogenation'. Proceedings 21st North American Catalysis Society Meeting.. FRIDMAN. FRIDMAN. BEESLEY. Nov. J. HOWARD. R. The majority of these benefits have been incorporated into the latest Catofin propane dehydrogenation plant design. CLARIANT INTERNATIONAL LTD Rothausstrasse 61 4132 Muttenz Switzerland CATALYSIS & ENERGY catalyst@clariant. 7.com WWW. nn An increase in the number of reactors that are operating in the dehydrogenation mode at the same time. 6. URBANCIC. 3.4.. Proceedings 22nd North American Catalysis Society Meeting.. isobutylene and butadiene producers.Z.'Butane Dehydrogenation at Billingham' Chem & Ind. WIPP.M. FRIDMAN.