Olefin Feed Research Articles

(Co‐)Oligomerization of Olefins to Hydrocarbon Fuels: Influence of Feed Composition and Pressure

AbstractThe co‐oligomerization of methanol‐based C2‐4 olefins on a heterogeneous nickel silica‐alumina catalyst enables the production of fuel‐range hydrocarbons. The objective of this study was the production of gasoline and jet fuel, which was achieved with an overall selectivity of above 90 %. The influence of olefin feed composition and pressure was investigated at 120 °C. By employing olefin mixtures instead of one single olefin, selectivity to specific chain lengths decreases and quantities of the individual products converge. An increase of olefin pressure from 16 to 32 bar slightly shifts the liquid products to shorter oligomers and raises feed conversion.

Advantages of Producing Aromatics from Propene over Ethene Using Zeolite‐Based Catalysts

AbstractSustainable production of aromatics, especially benzene, toluene and xylenes (BTX), is essential considering their broad applications and the current global transition away from crude oil utilization. Aromatization of lower olefins, particularly ethene and propene, offers great potential if they are derived from more circular alternative carbon feedstocks such as biomass and waste plastics. This work aims to identify the preferred olefin feed, ethene or propene, for BTX production in a fixed‐bed reactor. A commercial H‐ZSM‐5 (Si/Al = 23) catalyst was used as a reference catalyst, as well as a Ga‐ZSM‐5 catalyst, prepared by Ga ion‐exchange of the H‐ZSM‐5 catalyst. At 773 K, 1 bar, 45 vol % olefin, 6.75 h−1, propene aromatization over the Ga‐ZSM‐5 catalyst exhibited higher BTX selectivity of 55 % and resulted in slower catalyst deactivation compared to ethene aromatization.

Light olefin production by catalytic co-cracking of Fischer–Tropsch distillate with methanol and the reaction kinetics investigation

Abstract Catalytic co-cracking of Fischer–Tropsch (FT) light distillate and methanol combines highly endothermic olefin cracking reaction with exothermic methanol conversion over ZSM-5 catalyst to produce light olefins through a nearly thermoneutral process. The kinetic behavior of co-cracking reactions was investigated by different feed conditions: methanol feed only, olefin feed only and co-feed of methanol with olefins or F–T distillate. The results showed that methanol converted to C2–C6 olefins in first-order parallel reaction at low space time, methylation and oligomerization–cracking prevailed for the co-feed of methanol and C2–C5 olefins, while for C6–C8 olefins, monomolecular cracking was the dominant reaction whether fed alone or co-fed with methanol. For FT distillate and methanol co-feed, alkanes were almost un-reactive, C3–C5 olefins were obtained as main products, accounting for 71 wt% for all products. A comprehensive co-cracking reaction scheme was proposed and the model parameters were estimated by the nonlinear least square method. It was verified by experimental data that the kinetic model was reliable to predict major product distribution for co-cracking of FT distillate with methanol and could be used for further reactor development and process design.

Olefin Mixture Direct Sequence Retrofitting and Feed Compositions Sensitivity Analysis

The objective of this paper is to retrofit the energy of the Olefin Mixture (OM) direct sequence and analyze the energy sensitivity with respect to the feed compositions. In order to perform the retrofitting study and energy sensitivity analysis, a methodology for retrofitting the direct sequence and analyzing the energy sensitivity with respect to the feed compositions has been developed, consists of four stages. In Stage 1, a short-cut distillation column design method of process simulator (Aspen HYSYS) is used to simulate the direct sequence. Then, the energy used to separate individual component in the direct sequence is analyzed and taken as a reference. In Stage 2, an optimal OM sequence is determined using driving force method. All individual driving force curves for all adjacent components are plotted and the optimal sequence is determined based on the plotted driving force curves. Once the optimal OM sequence has been determined, the new optimal sequence is then simulated in Stage 3 using short-cut distillation column design method (using Aspen HYSYS), where the energy used in the optimal OM sequence is analyzed. Finally, the energy used in the optimal OM sequence is compared with the direct, direct-indirect and random sequence in Stage 4. The gains of each sequence are then calculated using the energy as the basis for the sensitivity analysis when the feed compositions are changed. From the results obtained, it can be concluded that it is possible to retrofit the direct sequence using the driving force method for better improvement in terms of energy consumptions and energy sensitivity.

Multicycle Investigation of Normal Paraffin Separation from Naphtha To Improve Olefin and Aromatic Feed

A programmed control double-column adsorber was built to investigate the steady operation of the normal paraffin separation from naphtha. The naphtha from Shanghai Gaoqiao Petrochemical Company (SGPC) was separated into a raffinate oil rich in non-normal hydrocarbons and a desorption oil rich in normal paraffins, using zeolite 5A as an adsorbent. In this paper, we investigate the effects of the adsorption/desorption temperature, feed space velocity, desorption gas space velocity, and switch time on the steady separation of normal paraffins. The adsorbability observed from the breakthrough curves of normal paraffins is consistent with the adsorption energies. The optimal conditions for the adsorption/desorption process were an operation temperature of 270 °C, a naphtha feed space velocity of 90.1 h–1, a switch time of 30 min, a desorption gas N2 space velocity of 127.5 h–1, and an intermediate oil cutting time of 2 min. With the Cutting Intermediate Oil (CIO) process, the normal paraffin content in raffinate oil was 3.42% and the potential aromatic content was 12.14% higher than that of naphtha. The normal paraffin content of desorption oil was 96.61%, and the ethylene yield was 15.08% higher than that of naphtha.

Green metrics analysis applied to the simultaneous liquid-phase etherification of isobutene and isoamylenes with ethanol over Amberlyst™ 35

A case study of the green metrics analysis of several processes is described. The considered system is the simultaneous etherification of isobutene and isoamylenes with ethanol over Amberlyst™ 35. Experimental results are compared under the green metrics methodology with those for the isolated ethyl tert -butyl ether and tert -amyl ethyl ether syntheses previously reported over acid ion-exchange resins using different reaction batch devices and different synthesis pathways, such as the production of both ethers from tertiary alcohols and from ethanol. The best results, from an environmental point of view, were obtained for ether syntheses from olefins and ethanol in terms of the parameters measured in the green metrics analysis. A process allowing the separation of ethers from the product stream and the reactants recirculation has been proposed and simulated. The suggested process depicts a suitable alternative for the simultaneous production of tertiary ethers from pure olefin feed and their downstream implementation as greener fuel additives with environmental benefits.

HYDROISOMERIZATION OF 1-PENTENE TO ISO-PENTANE IN A SINGLE REACTOR

It has been shown that hydroisomerization of an olefinic feed to an iso-paraffinic product can be performed in a single reactor using a platinum on mordenite (Pt-MOR) zeolite catalyst. This conversion finds application in a Fischer-Tropsch refinery where the syncrude is rich in olefins and conventional hydroisomerization would require hydrogenation of the feed as a feed pretreatment step. In order to demonstrate that the proposed process configuration is viable from a catalysis point of view, the hydroisomerization of 1-pentene over Pt-MOR has been investigated experimentally in the range 200°–270°C, 2 MPa, WHSV 1–3 h−1, and H2:1-pentene molar ratio of 3:1–5:1. The catalyst was stable during one week of continuous operation. The highest iso-pentane yield (69%) was obtained at 250°C. Side reactions (dimerization and cracking) increased with increasing temperature, decreasing H2:1-pentene ratio, and increasing space velocity.

Benzene Reduction by Alkylation in a Solid Phosphoric Acid Catalyzed Olefin Oligomerization Process

A refinery with a solid phosphoric acid olefin oligomerization unit can reduce the benzene content of its motor-gasoline by co-feeding the benzene-containing material to that unit. It has been shown that benzene co-feeding has little disruptive impact on olefin oligomerization, and >80% benzene conversion to alkylated benzenes has been demonstrated during a commercial test run on an industrial unit. Benzene conversion is insensitive to reactor inlet temperature in the range of 160−180 °C and remains better than 80% at liquid hourly space velocities of up to 1.5 h−1. A high propene content in the olefinic feed promotes benzene alkylation, and although butene-rich feeds can be employed, benzene conversion is lower.

Chain-Length Distributions Obtained over Nickel(II)-Exchanged or Impregnated Silica–Alumina Catalysts for the Oligomerization of Lower Alkenes

In the oligomerization of ethene, the chain-length distributions obtained over heterogeneous nickel catalysts at a low reaction temperature (ca. 110 °C) depend on the acidity of the silica–alumina support, the nickel loading and the olefin feed. Most significantly, ion-exchanged catalysts based on a silica–alumina of high acidity (ca. 0.7 mass% Ni), and those based on a highly-exchanged medium-acidity support (ca. 1.6% Ni), show a distinct superimposed activity for the dimerization of the intermediate butenes. This causes a desirable shift to higher hydrocarbon products, and it is possible to obtain 41 mass% C10+ oligomers, while the corresponding value predicted from Schulz–Flory statistics is only 24 mass%. No such deviation from Schulz–Flory statistics is observed in propene oligomerization.

Thermal Upgrading of Fischer−Tropsch Olefins

Thermal oligomerization is a radical based conversion process. It offers specific advantages to linear olefinic feed with a high α-olefin content, like primary Fischer−Tropsch products. Thermal oligomerization of C4−C14 Fischer−Tropsch feed materials has been investigated over the temperature range 320−400 °C. Motor gasoline, distillate, and lubricating oil quality was determined by the feed used, and operating conditions had only a minor influence. Good quality distillate (cetane ≥ 54) and lubricating oil (viscosity index of 100) could be produced, while the naphtha was suitable for chemical applications, like plasticizer alcohols production. Oxygenates present in the Fischer−Tropsch product had little influence on the process. Carbon formation was about 400 μg·g-1. Prospects for commercial application was discussed and is limited to an olefin-rich refining environment, where feed-specific advantages can be used to offset the disadvantage of a slow reaction rate (0.1 mol·s-1·m-3).

Development of an Empirical Model for Catalyst Lifetime in Isobutane/Butene Alkylation

Dimensional analysis of the governing equations in liquid-phase, solid-acid-catalyzed alkylation was used to develop an empirical model for the catalyst lifetime in terms of important operating variables. It was found that the dimensionless catalyst lifetime in a continuous stirred tank reactor was a function of four dimensionless groups, incorporating all important kinetic and operating variables. A power-law correlation was found to be adequate in representing the available experimental data. Because the alkylation reactions are highly diffusion-limited, it was shown that only three of the four exponents in the power-law correlation were independent. As such, the fourth exponent was obtained without a need to fit the correlation with its corresponding experimental data. The lifetime was found to be proportional to the concentration of active sites raised to the power of 0.8. Among the various operating variables, the olefin feed concentration most significantly influenced the catalyst lifetime.

Catalytic Polymerization and Post Polymerization Catalysis Fifty Years After the Discovery of Ziegler's Catalysts

AbstractDuring the 1950's the discoveries of Ziegler's organometallic catalyst systems and Natta's stereoselective olefin polymerization set the stage for extraordinary progress in polymer science and technology. Today advanced catalyst systems are available for catalytic carbon carbon bond formation by means of polyinsertion, metathesis, coupling reactions, and controlled radical polymerization. Modern catalytic olefin polymerization processes and polyolefins are environmentally friendly and meet the demands of a sustainable development. The architectures of homo‐ and copolymers based upon olefin, cycloolefin, diene, styrene and arene feed stocks are tailored as a function of single site catalysts' ligand frameworks. Polymer properties are varied over a very wide range, e.g., liquid/solid, rigid/soft, crystalline/amorphous/rubbery, permeable/impermeable, opaque/transparent, moldable/thermosetting, insulating/conducting. Advanced polymerization reaction engineering, copolymerization processes, reactor granule and reactor blend technologies, tailor‐made single site catalysts, catalyst blends and tandem catalysis improve property profiles, stability, morphology, and melt processing. Tuned cycloolefin polymers are new functional materials for electronic applications. Catalytic chain transfer (CCT) and atom transfer polymerization (ATRP) produce a variety of new functional polymers, reactive oligomers, and block copolymers. Aqueous polyolefin emulsions are obtained when catalytic olefin polymerization is performed in nanodroplets of catalyst miniemulsions. The scope of catalytic polymerization and post polymerization catalysis is progressing well beyond the frontiers of commodity polyolefin manufacturing. Advanced catalytic processes produce polar polymers such as polyethers, polyketones, polyesters, polycarbonates, polyamides, polyaramids, and polyimides. The new phosgene free polycarbonate syntheses are based upon the palladium catalyzed oxidative carbonylation. This overview highlights history, recent progress and modern trends in catalytic polymerization and catalytic polymer modification illustrated by selected examples. Ziegler's glass reactor for performing his Mülheim low pressure ethylene polymerization. The reactor is on display at the Max Planck Institut für Kohlenforschung in Mülheim (this picture was made available by courtesy of G. Fink).magnified imageZiegler's glass reactor for performing his Mülheim low pressure ethylene polymerization. The reactor is on display at the Max Planck Institut für Kohlenforschung in Mülheim (this picture was made available by courtesy of G. Fink).

Elucidation of n-Butane Isomerization on Sulfated Zirconia Using Olefin Addition

Olefin formation appears to play a key role in n-butane isomerization on sulfated zirconia (SZ). In order to better understand the pathway of the reaction, 1-butene (1-C 4 =) was added during reaction at low and at high reaction temperatures. Olefin addition, even at the lowest 1-C 4 =/ n-C 4 ratio, decreased the activity of the catalyst at 250°C, did not eliminate the reaction induction period, and contributed to catalyst deactivation from the beginning of the reaction. However, it shifted the maximum activity to lower time-on-stream (TOS). Butene added for only 90 s at the beginning of the reaction deactivated the catalyst in a manner similar to that in the case where it was added continuously during all TOS. Isotopic transient kinetic analysis (ITKA) showed that although more intermediates were initially formed on the surface with olefin addition, this positive effect was quickly overwhelmed by the negative effect of olefin concentration on deactivation. The positive impact of butene on the reaction was able to be more clearly seen at a lower reaction temperature (150°C) when deactivation was not as severe. The positive impact was manifested by an increase in the 5-min TOS reaction rate. Olefin addition also did not eliminate the induction period for reaction at this temperature. Even for these reaction conditions, catalyst deactivation was significant after 30 min TOS due to coke/oligomer formation. The increase in the reaction rate with the addition of olefin was due to an increase in the concentration of surface intermediates; no effect was seen on the average surface residence time for reaction, suggesting that the additional sites created were identical to those formed in the absence of added olefin. Butene added for only 2 min at the beginning of the reaction increased the activity of the catalyst during the next 250 min of reaction time, long after the olefin feed was terminated. Each added 1-butene molecule, thus, contributed to greater n-butane isomerization for many reaction cycles (ca. 700) beyond its elimination from the reactant stream, suggesting that it may have been instrumental in the formation of the additional active sites observed.

Deactivation behavior of the catalyst in solid acid catalyzed alkylation: effect of pore mouth plugging

The deactivation of solid acid catalysts in liquid-phase alkylation of isobutane with butenes was investigated. The role of pore mouth plugging, in particular, was studied and it was found that it had a significant effect on the deactivation behavior. Simple explicit correlations were developed for catalyst lifetime in a CSTR, both in terms of time-on-stream and butene turnover per catalyst weight. The correlations were tested using available experimental data from the literature and a reasonable agreement was observed. It was shown that for a zeolitic catalyst the butene turnover per catalyst weight was proportional to the square root of catalyst loading, while it was inversely proportional to both the olefin feed concentration and the square root of feed flow rate.

Supercritical alkylation and butene dimerization over sulfated zirconia and iron–manganese promoted sulfated zirconia catalysts

Supercritical alkylation and butene dimerization were investigated using sulfated zirconia (SZ) and iron–manganese promoted sulfated zirconia catalysts (SFMZ), as a function of iso-butane/olefin (I/O) ratio and at temperatures between 60 and 155°C. Detailed product analysis demonstrated that while C 8 yields were as high as 80 wt.%, neither catalyst produced significant quantities of trimethyl pentanes, although both had high selectivities to dimethyl hexenes. A comparison of 1-butene versus 2-butene as the olefin feed charge showed that 1-butene first isomerizes to 2-butene, which then produces C 8 products. In all cases, the products consisted primarily of C 8 olefins, which in turn was dominated by dimethyl hexenes. The addition of water at a concentration as low as 1.4 mol% was found to increase dimethyl hexene selectivity (94 wt.%), and lowered the deactivation rate by 30%. The dimerization of a straight 2-butene charge produced a C 5+ yield in excess of 90 wt.%, with a 73 wt.% selectivity to dimethyl hexenes. Subsequent regenerations of this catalyst resulted in about 10% conversion loss/generation, but with minimal change in dimethyl hexene selectivities.

Activity and Regenerability of Sulfated Zirconia Superacid Catalysts in Isobutane/1-Butene Alkylation

Alkylation of isobutane with 1-butene was carried out in the gas phase at atmospheric pressure over sulfate-promoted zirconia superacid catalysts prepared by two different procedure. The method of sulfation does not seem to much affect the surface area, superacidity, and crystalline phases present in the catalysts. However, sulfation by impregnation produces a catalyst with more acid sites in the weak and medium strength region. The catalysts showed high C 8 selectivity comparable to liquid acid catalysts; however, use of 1-butene as olefin feed reduces the selectivity toward trimethylpentanes. Increase of olefin space velocity and reaction temperature increases olefin conversion but dimerization of olefin was favored over alkylation. Although the catalysts lost their activity within initial few minutes, they could be regenerated by heating in air. Activity of the regenerated catalysts is slightly lower, but the selectivity remains nearly unchanged.

Liquid-Phase Synthesis of Ethanol-Derived Mixed Tertiary Alkyl Ethyl Ethers in an Isothermal Integral Packed-Bed Reactor

Industrial production of mixed tertiary ethers by reacting methanol or ethanol with a mixed tertiary olefin stream is a distinct possibility. Consequently, the synthesis of mixed ethyl tertiary alkyl ethers from ethanol and mixtures of reactive iso-olefins in an isothermal integral packed-bed reactor is studied. The rate expressions in terms of activities for the individual reaction rates in this family of ethers are taken from related work. These kinetic expressions are utilized here for comparison with experimental data obtained in a packed-bed reactor containing Amberlyst 15 ion-exchange resin catalyst for a mixed iso-C6 olefin feed stream as well as for a mixed C4, C5, and C6 iso-olefin stream. Etherification and isomerization conversions increase with space time at the lower temperatures; however, at the higher temperatures equilibrium limitations are approached. As a function of temperature, the conversions first increase and then decline due to thermodynamic limitations for these exothermic reactions. Good agreement is obtained between predictions and experiments.

Reforming of pyrolysis gasoline over platinum-alumina catalysts containing MFI type zeolites

Reforming of pyrolysis gasoline, a highly olefinic feed, has been carried out over Pt-alumina catalysts containing small amounts of MFI type zeolites. The incorporation of these zeolites helps in lowering the coke deposition on the catalysts, thereby increasing their life. Further, the products are virtually free of aliphatics. Due to the large concentration of aromatics in the feed, significant aromatic gain is obtained only at low pressures of operation.

Thermogravimetric analysis of the iso-butene oligomerization activity of various forms of synthetic mica-montmorillonite

AbstractThe iso-butene oligomerization activity of pure and metal-substituted synthetic mica-montmorillonite (SMM) was studied by simultaneous thermogravimetric-differential thermal analysis (TG-DTA). The incorporation of matrix Ni and ion-exchanged Co, Ni and Zn into SMM increased its iso-butene oligomerization activity while the presence of water in the olefinic feed reduced activity. These findings corresponded to trends found in previous work on high pressure (50 MPa) propene oligomerization over SMM and metal-substituted SMM.

Conversion of 1-butene to aromatics over AlPO 4-11

The activity of the crystalline molecular sieve AlPO 4-11 for the conversion of 1-butene to benzene, toluene, ethylbenzene, and the xylenes (BTEX) was followed as a function of temperature, time on stream, nickel loading, and methane dilution of the olefin feed. A maximum in liquid production, selectivity to BTEX, and cracking to C(1), C(2), and C(3) products was observed at 773 K. Over 8 h on stream at this temperature, selectivity to benzene and total liquid product increased significantly, the amount of cracked gases increased somewhat, and selectivity to toluene, ethylbenzene, and xylenes decreased somewhat. Nickel loading depressed the amount of BTEX produced probably due to rapid coking of the catalyst. Methane dilution of the feed stream caused a decrease in total liquid product but increased the liquid density as a result of changes in component selectivities. Even in the most favorable case, the activity of AlPO 4-11 was far less than that of HZSM-5 for the same reaction. The results support a mechanism that proceeds via partial dehydrogenation to butadiene which then participates in a dimerization step, possibly of a Diels-Adler type. C(1) to C(3) products arise from cracking of oligomers and not directly from the 1-butene feed.