Abstract: Processes and systems that utilize a fuel cell for carbon capture from a petrochemical stream that contains hydrogen and methane. The petrochemical stream can be the tail gas of a hydrocarbon cracking system, or any other petrochemical stream containing hydrogen and methane. The petrochemical stream can be separated into a hydrogen product stream and a methane product stream, before sending the methane product stream to the fuel cell. The fuel cell converts methane to carbon dioxide and hydrogen to water, while generating electricity that can be used to power equipment.

Abstract: The disclosure provides for a process for a non-catalytic oxidative coupling of methane reaction remarkable in that the process comprises a step of providing a counter-current shell-tube reactor comprising at least two tubes defining a tubular part and a shell part surrounding the tubular part and at least one inlet to feed a gaseous feed stream and at least one outlet to discharge a product stream; a step of providing a gaseous feed stream comprising a gas mixture of methane and oxygen in a defined molar ratio and preheated to a defined operating inlet temperature; a step of feeding the gaseous feed stream at least in the tubular part of the counter-current shell-tube reactor and a step of recovering a product stream.

Abstract: Apparatus and processes herein provide for converting hydrocarbon feeds to light olefins and other hydrocarbons. The processes and apparatus include, in some embodiments, feeding a hydrocarbon, a first catalyst and a second catalyst to a reactor, wherein the first catalyst has a smaller average particle size and is less dense than the second catalyst. A first portion of the second catalyst may be recovered as a bottoms product from the reactor, and a cracked hydrocarbon effluent, a second portion of the second catalyst, and the first catalyst may be recovered as an overhead product from the reactor. The second portion of the second catalyst may be separated from the overhead product, providing a first stream comprising the first catalyst and the hydrocarbon effluent and a second stream comprising the separated second catalyst, allowing return of the separated second catalyst in the second stream to the reactor.

Abstract: Methods and systems for the dehydrogenation of hydrocarbons include a direct contact condenser to remove compounds from an offgas process stream. The reduction of compounds can decrease duty on the offgas compressor by removing steam and aromatics from the offgas. The dehydrogenation reaction system can be applicable for reactions such as the dehydrogenation of ethylbenzene to produce styrene, the dehydrogenation of isoamiline to produce isoprene, or the dehydrogenation of n-pentene to produce piperylene.

Abstract: An apparatus for making a gaseous clathrate has a closed reaction vessel to which are fed a reaction gas and a reaction liquid while an interior of the vessel is maintained at a predetermined pressure and a predetermined temperature so that the gaseous clathrate is formed in the vessel. An outlet nozzle on the vessel defines a flow passage opening into the vessel and having an inner wall surface extending between an inner inlet end inside the vessel and an outer outlet end. The passage extends along an axis, is rotation-symmetrical about the axis, and is of decreasing flow cross section from its inner end to its outer end. The inner wall surface is curved in an S-shape from the inner end to the outer end so that pressure in the vessel forces the formed clathrate out through the passage with increasing compression as the flow cross section decreases.

Abstract: A method for the oxidative coupling of hydrocarbons includes providing an oxidative catalyst inside a reactor and carrying out the oxidative coupling reaction under a set of reaction conditions. The reactor surfaces that contact the reactants and products do not provide a significant detrimental catalyzing effect. In an embodiment the reactor contains an inert lining or a portion of the reactor inner surface is treated to reduce the detrimental catalytic effects. In an embodiment the reactor contains a lining that includes an oxidative catalyst.

Abstract: A process for making ethylbenzene and/or styrene by reacting toluene with methane in one or more microreactors is disclosed. In one embodiment a method of revamping an existing styrene production facility by adding one or more microreactors capable of reacting toluene with methane to produce a product stream comprising ethylbenzene and/or styrene is disclosed.

Abstract: A thermal cracking tube is adapted to suppress pressure losses while maintaining heat transfer promoting effect on the fluid inside the tube. The tube has a plurality of projections rows extending circumferentially along inner surface of the tube orthogonal to or as inclined with respect to the axis of tube, each of the projection rows including a plurality of projections provided on the tube inner surface. The tube is defined by S/10?D=0.2?0.7, h/D=0.02?0.05 and L/?D=0.04?0.5. D is inner diameter of the tube, h is height of projection A arbitrarily chosen in a projection row ?, L is length of circular arc of projection A in a direction orthogonal to tube axis, and S is area of a region R surrounded by projection A, phantom lines L1 and L2 (extending respectively from circumferentially opposite ends of projection A in parallel to tube axis) and projection row ? downstream from projection row ?.

Abstract: A process is proposed for continuously operating a plant for preparing acetylene from hydrocarbons by partial oxidation, cleavage in an arc or pyrolysis of hydrocarbons to obtain a reaction gas mixture which is conducted through one or more compressors, the pressure of the reaction gas mixture on the suction side of the compressor being controlled within a predefined range by means of a conventional controller, which comprises additionally using a higher-level model-supported predictive controller which reacts to abrupt changes in the mass flow rate of the reaction gas mixture.

Abstract: A method for the separation of hydrocarbon compounds utilizing a dividing wall distillation column is described. The dividing wall distillation column enables one or more side draw stream to be removed from the dividing wall distillation column in addition to an overhead stream and a bottoms stream.

Abstract: The present invention relates to piping (1) for use in industrial activities, where the piping (1) has a specific geometry. In particular, the piping (1) is formed as a lowamplitude helix, which causes fluid flowing through the piping (1) to swirl. This swirl flow provides a large number of advantages. Particular applications where the piping (1) can be used include petroleum production risers and flowlines, production tubing for downhole use in wells, pipelines for the transportation of fluids, static mixers, bends, junctions or the like, penstocks and draft tubes, reactors for chemical, petrochemical, and pharmaceutical applications, heat exchangers, cold boxes, incinerators and furnaces for waste disposal, static separators, and air intakes.

Abstract: A process for making ethylbenzene and/or styrene by reacting toluene with methane is disclosed. In one embodiment the process can include reacting toluene with methane to form a product stream comprising ethylbenzene and further processing the ethylbenzene to form styrene in an existing styrene production facility.

Abstract: A process for making ethylbenzene and/or styrene by reacting toluene with methane in one or more microreactors is disclosed. In one embodiment a method of revamping an existing styrene production facility by adding one or more microreactors capable of reacting toluene with methane to produce a product stream comprising ethylbenzene and/or styrene is disclosed.

Abstract: A process is proposed for continuously operating a plant for preparing acetylene from hydrocarbons by partial oxidation, cleavage in an arc or pyrolysis of hydrocarbons to obtain a reaction gas mixture which is conducted through one or more compressors, the pressure of the reaction gas mixture on the suction side of the compressor being controlled within a predefined range by means of a conventional controller, which comprises additionally using a high-level model-supported predictive controller which reacts to abrupt changes in the mass flow rate of the reaction gas mixture.

Abstract: Process for the preparation of acetylene from hydrocarbons by partial oxidation, arc cleavage or pyrolysis, the material stream comprising the acetylene and soot obtained being fed to a compressor, wherein a liquid which takes up the major part of the soot present in the material stream is sprayed into the compressor.

Abstract: The disclosed invention relates to a process for converting ethylbenzene to styrene, comprising: flowing a feed composition comprising ethylbenzene in at least one process microchannel in contact with at least one catalyst to dehydrogenate the ethylbenzene and form a product comprising styrene; exchanging heat between the process microchannel and at least one heat exchange channel in thermal contact with the process microchannel; and removing product from the process microchannel. Also disclosed is an apparatus comprising a process microchannel, a heat exchange channel, and a heat transfer wall positioned between the process microchannel and heat exchange channel wherein the heat transfer wall comprises a thermal resistance layer.

Abstract: The present invention provides a reactor system having: (1) a plurality of reactors connected in fluid flow communication and having at least one pair of reactors separated by an interstage position; (2) a line for supplying a reactant feed stream separately to an inlet of more than one of the plurality of reactors; and (3) a diverter in fluid communication with the interstage position and capable of directing a first portion of a product stream exiting one reactor in said pair of reactors to a first location and a second portion of the product flow stream to an inlet of another reactor in said pair of reactors.

Abstract: Methods of dehydrogenating hydrocarbons to yield unsaturated compounds are described. Reactor configurations useful for dehydrogenation are also described. Hydrocarbons can be dehydrogenated, for relatively long periods of time-on-stream, in a reaction chamber having a dimension of 2 mm or less to produce H2 and an olefin. Techniques have been developed that reduce coke and allow stable, relatively long-term operation in small reactors.

Abstract: A process for independently and concurrently cracking at least two different hydrocarbon feedstocks to olefins. The process is carried out in a furnace for cracking hydrocarbon feed which has at least a first and second independent radiant cracking zone to produce a first cracked product and second cracked product that are separately withdrawn from the furnace.

Abstract: A method for maximizing the contact between solid catalyst particles and a feedstock while minimizing undesirable side reactions is provided. A plurality of feedstock jets are contacted with solid catalyst particles in a reactor having a non-homogenous contact zone and a unified flow contact zone.

Abstract: A process for steam cracking liquid hydrocarbon feedstocks containing synthetic crude oil comprises i) hydroprocessing a wide boiling range aliquot containing a) normally liquid hydrocarbon portion substantially free of resids and b) thermally cracked hydrocarbon liquid, boiling in a range from about 600° to about 1050° F., to provide a synthetic crude oil substantially free of resids; ii) adding to the synthetic crude oil a normally liquid hydrocarbon component boiling in a range from about 100° to about 1050° F.; and iii) cracking the mixture resulting from ii) in a cracker furnace comprising a radiant coil outlet to provide a cracked effluent, wherein the cracking is carried out under conditions sufficient to effect a radiant coil outlet temperature which is greater than the optimum radiant coil outlet temperature for cracking the synthetic crude oil separately. A method for upgrading synthetic crude for use in cracking is also provided, as well as a feedstock for cracking.

Abstract: A process for contacting a bed of particulate material, usually catalyst, with a transverse flow of fluid is disclosed. The particulate material moves or is prevented from not moving, while the fluid passes through the bed at a rate greater than the stagnant bed pinning flow rate. This invention is applicable to hydrocarbon conversion processes and allows for higher fluid throughput rates compared to prior art processes.

Abstract: This invention provides feed introduction devices, and processes for using same, which minimize catalyst clogging. In particular, the invention is to a feed introduction device having a first end in fluid communication with a feed source, a second end in fluid communication with a reactor and a deviation zone between the first end and the second end to deviate the flow of feed about a deviation angle from the first end toward the second end. According to the invention, the deviation angle is greater than 90 degrees.

Abstract: A novel apparatus for producing sweet synthetic crude from a heavy hydrocarbon feed includes: an upgrader for receiving the heavy hydrocarbon feed and producing a distillate fraction including sour products, and high-carbon content by-products; a gasifier for receiving the high-carbon content by-products and producing synthetic fuel gas and sour by-products; a hydroprocessing unit for receiving the sour by-products and hydrogen gas, thereby producing gas and sweet crude; and a hydrogen recovery unit for receiving the synthetic fuel gas and producing further hydrogen gas and hydrogen-depleted synthetic fuel gas, the further hydrogen gas being supplied to the hydroprocessing unit.

Abstract: The invention provides methods of oxidative dehydrogenation (ODH). Conducting ODH in microchannels has unexpectedly been found to yield superior performance when compared to the same reactions at the same conditions in larger reactors. ODH methods employing a Mo—V—Mg—O catalyst is also described. Microchannel apparatus for conducting ODH is also disclosed.

Abstract: The present invention is directed to a hydrocarbon conversion apparatus and process. The apparatus comprises the following: a plurality of riser reactors, each having a first end into which a catalyst is fed, a second end through which the catalyst can exit, and optionally a center axis extending therebetween. The apparatus also includes a separation zone having a plurality of inlets, each inlet not being oriented along the center axes of the riser reactors, the separation zone being provided to separate the catalyst from products of a reaction conducted in the hydrocarbon conversion apparatus. A plurality of deviating members are also provided, each deviating member being in fluid communication between the second end of a respective riser reactor and a respective inlet of the separation zone. The apparatus also includes a catalyst retention zone provided to contain catalyst, which is fed to the riser reactors.

Abstract: There is disclosed a process for producing an ?-olefin oligomer by subjecting an ?-olefin to oligomerization reaction in the presence of a catalyst and an organic solvent which comprises the step of spraying a solvent containing the organic solvent in the form of a linear or bar-like pressure fluid toward a wall surface of a vapor phase portion of a reactor from a nozzle fitted within a space of the vapor phase portion of the reactor to conduct the oligomerization reaction while cleaning the wall surface of the vapor phase portion of the reactor. In the production process of the present invention, it is possible to effectively prevent deposition of polymers onto the wall surface of the vapor phase portion of the reactor and stably operate the reactor for a long period of time.

Abstract: A method of operating a multi-phase downflow reactor so as to induce a pulsing flow regime is disclosed. The pulse may be induced by increasing the gas rate while maintaining the liquid rate until a pressure drop sufficient to induce the pulse flow is achieved. The method is particularly useful in the sulfuric acid catalyzed alkylation of olefins in a reactor packed with a stainless steel/polypropylene mesh.

Abstract: A process for contacting a bed of particulate material, usually catalyst, with a transverse flow of fluid is disclosed. The particulate material moves or is prevented from not moving, while the fluid passes through the bed at a rate greater than the stagnant bed pinning flow rate. This invention is applicable to hydrocarbon conversion processes and allows for higher fluid throughput rates compared to prior art processes.

Abstract: A device has a reaction chamber with at least one feed inlet (5) and at least one evacuation outlet (10). An outside jacket (2a) that is resistant to internal pressure is positioned around the device and contains at least one module (44) through which a reagent and formed products circulate. The module (44) has walls (11) and (12) made of refractory material that are included in a sealed jacket (40). The sealed jacket (40) is connected by a flexible connection to the jacket (2a) and to a heat exchanger that is also linked to the module (44) and to the jacket (2a) by a flexible connection.

Abstract: A process for the dehydrogenation of a C2 or C3 alkyl aromatic compound to a corresponding vinyl aromatic compound in a tubular reactor incorporating a spiral flow path. Preferred embodiments of the invention provide processes for the production of styrene or divinylbenzene by the catalytic dehydrogenation of ethylbenzene or diethylbenzene, respectively. A feedstock containing a C2 or C3 alkyl aromatic and steam is supplied into the inlet of a tubular reactor containing a dehydrogenation catalyst and comprising a hydrogen permeable outer wall. The alkyl aromatic compound is dehydrogenated to a corresponding vinyl aromatic compound with the attendant production of hydrogen. The feedstock and products of the dehydrogenation reactor are flowed along a longitudinal spiral flow path providing for an outward radial flow of hydrogen to provide a pressure gradient through the hydrogen permeable outer wall of the reactor with the flow of hydrogen therethrough. Hydrogen is removed from the outer wall of the reactor.

Abstract: The present invention provides a pyrolysis tube for enhancing the yield of olefins and reducing a coking tendency in steam cracking of hydrocarbons. According to the present invention, the pyrolysis tube is characterized in that a plurality of mixing blades made by twisting two ends of a plate in opposite directions are included therein. The yield of ethylene is thereby improved and the coking tendency is reduced by mixing a fluid flow, improving a heat transfer rate and shortening a residence time of the reactants therein.

Abstract: The invention is a process and the corresponding apparatus for producing light olefins from oxygenates in an OTO reactor comprising sending an oxygenate feed stream through a feed stream distributor into an OTO reactor, contacting the oxygenates with a catalyst to produce a mixture comprising light olefins, diolefins, unreacted oxygenate and other by-products; separating the unreacted oxygenate and diolefins from said light olefins and said by-products; and returning the unreacted oxygenate and diolefins to the OTO reactor. The unreacted oxygenate and diolefins are sent through at least one feed nozzle into said reactor at a point separate from the oxygenate feed stream.

Abstract: The present invention is directed to a hydrocarbon conversion apparatus. The apparatus comprises the following: a plurality of riser reactors, each of the riser reactors having a first end into which a catalyst can be fed and a second end through which the catalyst can exit the riser reactor; a separation zone into which the second ends of the riser reactors extend, the separation zone being provided to separate the catalyst from products of a reaction conducted in the hydrocarbon conversion apparatus; and at least one catalyst return in fluid communication with the separation zone and the first ends of the riser reactors, the catalyst return being provided to transfer the catalyst from the separation zone to the first ends of the riser reactors.

Abstract: The present invention relates to a process for pyrolysis of hydrocarbons for olefin preparation, and particularly to a process for pyrolysis of hydrocarbons comprising pyrolyzing paraffin hydrocarbons in the presence of steam to prepare olefins, where the pyrolysis is conducted in a pyrolysis reaction tube in which a porous inorganic substance with a pore diameter of 1 ?m˜5 mm, a porosity of 10˜80%, and a maximum specific surface area of 0.1 m2/g is inserted or filled. According to the present invention, in the hydrocarbon pyrolysis process, the porous inorganic substance is inserted or filled into the pyrolysis reaction tube, and thus the olefin yield can be improved compared to the conventional pyrolysis processes, a continuous operation period can be prolonged, and a life cycle of the pyrolysis reaction tube can be prolonged.

Abstract: A process for contacting a bed of particulate material, usually catalyst, with a transverse flow of fluid is disclosed. The particulate material moves or is prevented from not moving, while the fluid passes through the bed at a rate greater than the stagnant bed pinning flow rate. This invention is applicable to hydrocarbon conversion processes and allows for higher fluid throughput rates compared to prior art processes.

Abstract: The present invention discloses a process and apparatus for improving the catalyst life and efficiency in a gas flow catalyst bed reactor assembly. The reactor comprises an outer reaction vessel, an inner displacement cylinder, and an annular catalyst bed surrounding the displacement cylinder having a top half and a bottom half. Fluid flow improvement is achieved by adding at least one baffle to the top half of the displacement cylinder to improve uniformity of fluid flow in the reaction vessel and across the catalyst bed. Also disclosed is a process for improving fluid flow uniformity in a gas phase reactor comprising an outer reaction vessel, an inner displacement vessel having a top half and a bottom half and a reaction outer surface and an inert inner space, and an annular catalyst bed. The process comprises conducting fluid flow simulations using actual reactor conditions. During simulation, baffles are added on the outer reaction surface of the displacement reactor to improve simulated fluid flow.

Abstract: A novel apparatus for producing sweet synthetic crude from a heavy hydrocarbon feed comprising: an upgrader for receiving said heavy hydrocarbon feed and producing a distillate fraction including sour products, and high-carbon content by-products; a gasifier for receiving the high-carbon content by-products and producing synthetic fuel gas and sour by-products; a hydroprocessing unit for receiving the sour by-products and hydrogen gas, thereby producing gas and sweet crude; and a hydrogen recovery unit for receiving said synthetic fuel gas and producing further hydrogen gas and hydrogen-depleted synthetic fuel gas, said further hydrogen gas being supplied to said hydroprocessing unit.

Abstract: A process for recovering crude 1,3-butadiene from a C4 fraction by extractive distillation using a selective solvent in a dividing wall column (TK) in which a dividing wall (T) is arranged in the longitudinal direction of the column to form a first subregion (A), a second subregion (B) and a lower common column region (C) and which is preceded by an extractive scrubbing column (K) is proposed.

Abstract: A novel apparatus for producing sweet synthetic crude from a heavy hydrocarbon feed comprising: an upgrader for receiving said heavy hydrocarbon feed and producing a distillate fraction including sour products, and high-carbon content by-products; a gasifier for receiving the high-carbon content by-products and producing synthetic fuel gas and sour by-products; a hydroprocessing unit for receiving the sour by-products and hydrogen gas, thereby producing gas and sweet crude; and a hydrogen recovery unit for receiving said synthetic fuel gas and producing further hydrogen gas and hydrogen-depleted synthetic fuel gas, said further hydrogen gas being supplied to said hydroprocessing unit.

Abstract: A process for converting hydrocarbons in the presence of a catalyst is described that is carried out in a three-phase reactor in which the liquid Peclet number is in the range 0 (excluded) to about 10, with a superficial gas velocity Ug that is preferably less than 35 cm.s−1, to encourage gas transfer into the liquid phase and avoid too much attrition of the catalyst grains.

Abstract: Disclosed is a fluidized bed reactor wherein the average cross-sectional area occupied by a cooling coil, a dummy pipe and/or a cyclone leg is 10% or more of the average cross-sectional area of said reactor in a dense-phase fluidized catalyst bed region. The fluidized bed reactor in the present invention allows an improved fluidization of catalyst and thus allows an efficient reaction of a hydrocarbon with an oxygen-containing gas in the presence of a catalyst.

Abstract: A process for upgrading a liquid petroleum or chemical stream wherein said stream flows countercurrent to the flow of a treat gas, such as a hydrogen-containing gas, in at least one reaction zone. The temperature of at least a portion of the liquid stream in the reactor is used to control the flooding characteristics of the reactor.

Abstract: A slurry Fischer-Tropsch hydrocarbon synthesis process for synthesizing liquid hydrocarbons from synthesis gas, in a hydrocarbon synthesis reactor, also hydroisomerizes the synthesized hydrocarbons in one or more external downcomer reactor hydroisomerizing loops outside of the reactor, but which are a part of the synthesis reactor. A monolithic catalyst is used for the hydroisomerization, and slurry circulation between the synthesis reactor and the one or more hydroisomerization loops is achieved, at least in part, by density-difference driven hydraulics created by removing gas bubbles from the slurry passed into the loop. Preferably, catalyst particles are also removed before the slurry contacts the monolithic hydroisomerization catalyst.

Abstract: A slurry Fischer-Tropsch hydrocarbon synthesis process for synthesizing liquid hydrocarbons from synthesis gas in a synthesis reactor also hydroisomerizes the synthesized hydrocarbons in one or more external lift reactor hydroisomerizing loops outside of the reactor, but which are a part of the reactor. A monolithic catalyst is used for the hydroisomerization and slurry circulation between the synthesis reactor and one or more loops is achieved, at least in part, by the lift action of a hydrogen treat gas injected into each loop.

Abstract: A method and apparatus for alkylating an alkylation substrate with an alkylating agent in the presence of solid catalyst particles in a transport reactor is disclosed. Solid catalyst particles in the transport reactor effluent recirculate to the inlet of the transport reactor through one or more conduits. The rate through each conduit is regulated by fluid-controlled valves that use the alkylation substrate as the regulating fluid. This method and apparatus help ensure uniform or symmetric flow of catalyst from the effluent of the transport reactor to the bottom of the transport reactor. This method and apparatus also help ensure uniform or symmetric flow of alkylation substrate to the bottom of the transport reactor with minimal bypassing by the alkylating agent around of the transport reactor. This invention finds use in the production of motor fuels by the alkylation of liquid hydrocarbons in the presence of solid catalyst particles.

Abstract: A process for thermal and, optionally, catalytic upgrading and hydrogenation of hydrocarbons is described, wherein the hydrocarbons (oil) with a lower API grade is passed through one or more reactors connected in parallell or in series, preferably in series, in liquid state where it under pressure and intense agitation at a given temperature is thermally upgraded by increasing API, and that the product is discharged in liquid state, and whereby the agitation is effected by whipping elements, optionally made of a catalytic material acting as a catalyst in upgrading the oil in the reactor.

Abstract: Vapor phase alkylation of an aromatic substrate in a multi-stage alkylation reaction zone having a plurality of series-connected catalyst beds providing mixing zones between adjacent catalyst beds. An aromatic substrate and a C2-C4 alkylating agent is supplied to an inlet side of a gas phase reaction zone causing vapor phase alkylation of the aromatic substrate as the aromatic substrate and the alkylating agent flow through the reaction zone from one catalyst bed to the next. A quench fluid comprising one or both of the aromatic substrate and the alkylating agent is supplied into the interior of the mixing zone through a plurality of flow paths. One portion of the flow paths is directed upwardly and another portion downwardly within the mixing zone. The quench fluid is supplied to the mixing zone through a plurality of dispersion channels spaced laterally from one another.

Abstract: A process for hydrocarbon conversion to prepare lower olefins such as ethylene, propylene, etc., and light aromatics by bringing hydrocarbons into contact with a solid granular catalyst. In order to optimize the reaction conditions and product structure and save the capital and operating costs, a piston flow reactor is used in this process and multiple groups of feed inlets, which allow hydrocarbons with different properties to enter the device from different feed inlets and proceed pyrolysis under different operation conditions, are set on the reactor. This process is usable for individual pyrolysis or co-feed pyrolysis of hydrocarbons from refinery gases, liquid hydrocarbons, to heavy residues.

Abstract: Process for the catalytic dehydrogenation of a C2 or C3 alkyl aromatic in which a feedstock containing the alkyl aromatic and steam is supplied into the inlet of a tubular reactor containing a dehydrogenation catalyst. Within the reactor, the feedstock flows through at least a portion of the reactor along a spiral flow path extending longitudinally of the reactor. The resulting vinyl aromatic product is then recovered from a downstream or outlet section of the reactor. The spiral flow path through which the feedstock is passed is located at least adjacent the inlet side of the reactor and at least a portion of the spiral flow path contains a particulate dehydrogenation catalyst. The spiral flow path may extend throughout a major portion of the elongated tubular reactor and may contain a particulate dehydrogenation catalyst in a substantial portion there.