WO2014099572A1

WO2014099572A1 - Process for producing hydrogen cyanide using a distributor plate

Info

Publication number: WO2014099572A1
Application number: PCT/US2013/074548
Authority: WO
Inventors: John C. Caton; Bren J. STAHLMAN; Kevin L. HAMMACK
Original assignee: Invista Technologies S.A R.L.
Priority date: 2012-12-18
Filing date: 2013-12-12
Publication date: 2014-06-26
Also published as: CN103864113B; HK1199003A1; CN103864113A; TW201439001A; TWI519479B

Abstract

A distributor plate is disclosed for a hydrogen cyanide reaction process that breaks the jet flow of the ternary gas mixture and assists to evenly distribute the ternary gas mixture across a catalyst bed. The distributor plate operates with a low pressure drop.

Description

PROCESS FOR PRODUCING HYDROGEN CYANIDE USING

A DISTRIBUTOR PLATE

CROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. App. No. 61/738,773, filed December 18, 2012, the entire contents and disclosures of which are incorporated herein.

FIELD OF THE INVENTION

[0002] The present invention relates to a process for producing hydrogen cyanide and more particularly, to a converter comprising a distributor plate to break a jet flow of the ternary gas mixture and for assisting in distributing a ternary gas mixture over a catalyst bed, and to processes for using the distributor plate.

BACKGROUND OF THE INVENTION

[0003] Conventionally, hydrogen cyanide ("HCN") is produced on an industrial scale according to either the Andrussow process or the BMA process. (See e.g., Ullman's Encyclopedia of Industrial Chemistry, Volume A8, einheim 1987, pages 161-163). For example, in the Andrussow process, HCN can be commercially produced by reacting ammonia with a methane-containing gas and an oxygen-containing gas at elevated temperatures in a reactor in the presence of a suitable catalyst (U.S. Patent Nos. 1,934,838 and 6,596,251). Sulfur compounds and higher homologues of methane may have an effect on the parameters of oxidative ammonolysis of methane. See, e.g., Trusov, Effect of Sulfur Compounds and Higher Homologues of Methane on Hydrogen Cyanide Production by the Andrussow Method, Russian J. Applied Chemistry, 74:10 (2001), pp. 1693-1697). Unreacted ammonia is separated from HCN by contacting the reactor effluent gas stream with an aqueous solution of ammonium phosphate in an ammonia absorber. The separated ammonia is purified and concentrated for recycle to HCN conversion. HCN is recovered from the treated reactor effluent gas stream typically by absorption into water. The recovered HCN may be treated with further refining steps to produce purified HCN. Clean Development Mechanism Project Design Document Form (CDM PDD, Version 3), 2006, schematically explains the Andrussow HCN production process. Purified HCN can be used in hydrocyanation, such as hydrocyanation of an olefin-containing group, or such as hydrocyanation of 1,3 -butadiene and pentenenitrile, which can be used in the manufacture of adiponitrile ("ADN"). In the BMA process, HCN is synthesized from methane and ammonia in the substantial absence of oxygen and in the presence of a platinum catalyst, resulting in the ' production of HCN, hydrogen, nitrogen, residual ammonia, and residual methane. (See e.g., Ullman's Encyclopedia of Industrial Chemistry, Volume A8, Weinheim 1987, pages 161-163). Commercial operators require process safety management to handle the hazardous properties of hydrogen cyanide. (See Maxwell et al. Assuring process safety in the transfer of hydrogen cyanide manufacturing technology, JHazMat 142 (2007), 677-684). Additionally, emissions of HCN production processes from production facilities may be subject to regulations, which may affect the economics of HCN manufacturing. (See Crump, Economic Impact Analysis For The Proposed Cyanide Manufacturing NESHAP, EPA, May 2000).

[0004] In producing HCN, the ammonia gas, methane-containing gas and oxygen- containing gas are mixed to form a ternary gas mixture that is fed to the reactor. The ternary gas mixture contacts the catalyst bed. Typically the catalyst bed has a diameter that is larger than the feed pipe to the reactor and the ternary gas mixture needs to be distributed over the catalyst bed. Flame arrestors, which are primarily used to prevent flash back, have been used to distribute the ternary gas mixture as described in U.S. Pat. Nos. 2,620,259; 6,491,876; and 6,656,442. U.S. Pat. No. 3,215,495 describes a layer of inert alumina-silica refractory fiber covered by a layer of inert refractory particles, which aids in the distribution of the feed gas over the catalyst bed to avoid hot spots.

[0005] U.S. Pat. No. 3,423,185 describes a grate for supporting metallic gauze catalysts in a reactor in which ammonia and methane are reacted to produce HCN, the grate comprising a number of horizontally arranged ceramic blocks with holes therethrough for the passage of reactant gases, the upper part of the grate comprising a catalyst contact means for supporting the gauze catalyst and the lower part of the grate comprising a gas distribution means for uniformly distributing reactant gases across the cross-section of the reactor.

[0006] U.S. Pat. No. 6,221,327 discloses an improved catalyst system utilizing flow through radiation shielding of the reaction zone and to processes for using the catalyst system for the production of hydrogen cyanide. The radiation shield of the catalyst system may be formed of two or more layers of the radiation shielding. In some applications wherein there is no concern regarding a pressure drop across the radiation shield, multiple layers or a thicker shield may be used, to generate such a pressure drop, for purposes of further improving flow distribution through the system. [0007] U.S. Pat. No. 8,133,458 discloses a reactor for converting methane, ammonia and oxygen and alkaline or alkaline earth hydroxides into alkaline or alkaline earth cyanides by two- stage reactions comprising a first stage with a gas inlet, wherein the first stage is formed by a cone with distributor plates providing an even gas distribution over the catalyst material wherein the distributor plates are located between the gas inlet of the reactor and catalyst material and the distributor plates being perforated with a number of holes, with the distributor plates spaced from each other in the flow direction of the gas, the first distributor plate(s) functioning mainly to distribute the gas, whereas the last distributor plate works as a heat radiation shield and as a distributor plate facing the catalyst material, and wherein the catalyst material is present in the form of catalyst gauze fixed by catalyst weights.

[0008] In general, a high pressure drop is needed to ensure adequate distribution of the ternary gas mixture. However, a high pressure drop would cause a loss of productivity. Thus, what is needed is improved distribution of the reactant gases over the catalyst bed suitable for HCN production.

SUMMARY OF THE INVENTION

[0009] One embodiment of the present invention is directed to a converter for preparing hydrogen cyanide comprising an elongated conduit for introducing at least one reactant gas selected from the group consisting of a methane-containing gas, ammonia-containing gas, an oxygen-containing gas, and mixtures thereof, wherein the elongated conduit produces a ternary gas mixture flow, preferably having at least 25 vol.% oxygen; a reactor vessel comprising an inlet port for receiving the ternary gas mixture, a flame arrestor, and a catalyst bed; and a distributor plate being disposed within the reactor vessel downstream of the inlet port and upstream of the flame arrestor, the distributor plate having a diameter that is greater than the inlet port and less than a maximum diameter of the reactor vessel, wherein the distributor plate has a void area that is at least 50% to 80%, e.g., from 50% to 75%, of the total area of the distributor plate and wherein the distributor plate comprises a solid area that is aligned with a centerpoint of the inlet port. In one aspect, the solid area and inlet port may be concentrically aligned. The distributor plate may be aligned transverse to the flow of the ternary gas mixture. The solid area may have a raised portion that is conical-shaped. The raised portion may be rigidly affixed to the distributor plate. The converter may further comprise one or more arm braces which connect the distributor plate to an internal wall of the reactor vessel. Each of the one or more arm braces may be mounted to a downstream surface of the distributor plate. The void area may be defined by a plurality of holes . Each of the holes of the plurality of holes may have a diameter from 0.1 mm to 20 mm. The flame arrestor may comprise a refractory ceramic material. The refractory ceramic material may be selected from the group consisting of ceramic foam, ceramic blankets, pills, alumina-silica refractory non-woven blankets and combinations thereof. The solid area may have a diameter that is less than or equal to the outlet of the elongated conduit. The distributor plate may have a diameter ranging from 10 cm to 290 cm. The convertor may further comprise a circumferential opening between internal walls of the reactor vessel and a circumference of the distributor plate. The solid area may be defined by one or more removable devices inserted in at least a portion of the plurality holes, so that the distributor plate has a void area that is from 50% to 80% of the total area of the distributor plate. The one or more removable devices may be selected from the group consisting of bolts, rivets, threaded inserts, forged hardware, or combinations thereof. In one aspect, the solid area may comprise a raised portion having a conical shape. The raised portion is mounted directed to the distributor plate.

[0010] A second embodiment of the present invention is directed to a convertor for preparing hydrogen cyanide comprising an elongated conduit for introducing at least one reactant gas selected from the group consisting of a methane-containing gas, an ammonia-containing gas, an oxygen-containing gas, and mixtures thereof, wherem the elongated conduit produces a ternary gas mixture flow; a reactor vessel comprising an inlet port for receiving the ternary gas mixture, a flame arrestor, and a catalyst bed; and a distributor plate disposed within the reactor vessel downstream of the inlet port and upstream of the flame arrestor, wherein the distributor plate has a void area defined by a plurality of holes that is from 50% to 80% of the total area of the distributor plate and wherein the distributor plate comprises a solid area having raised portion that is conical-shape.

[0011] A third embodiment of the present invention is directed to a process for producing hydrogen cyanide, comprising providing a ternary gas mixture comprising a methane-containing gas, an ammonia-containing gas, and an oxygen-containing gas, to at least one inlet port of a reactor vessel; passing at least a portion of the ternary gas mixture through a distributor plate to form an evenly distributed gas mixture, wherein the distributor plate is disposed within the reactor vessel downstream of the inlet port, the distributor plate having a diameter that is greater than the inlet port and less than a maximum internal diameter of the reactor vessel, wherein the distributor plate has a void area that is at least 50% to 80%, e.g., 50% to 75%, of the total area of the distributor plate and wherein the distributor plate comprises a solid area that is aligned with a centerpoint of the inlet port; contacting the evenly distributed gas mixture with a catalyst in the reactor vessel to provide a reaction product comprising hydrogen cyanide; and recovering the hydrogen cyanide from at least one outlet port of the reactor. In one embodiment, the evenly distributed gas mixture has a coefficient of variation that is less than 0.1 across the diameter of the catalyst bed. The reactor vessel may further comprise a flame arrestor that is downstream of the distributor plate, wherein the flame arrestor comprises a refractory ceramic material. The ternary gas mixture may have a coefficient of variation that is less than 0.1 across the diameter of the catalyst bed, preferably less than 0.05 across the diameter of the catalyst bed. The pressure drop in the reactor vessel may be less than 150 kPa. The ternary gas mixture may comprise at least 25 vol.% oxygen. The oxygen-containing gas may comprise at least 80 vol.% oxygen. The ternary gas mixture may have a molar ratio of ammonia-to-oxygen from 1.2 to 1.6 and a molar ratio of methane-to-oxygen from 1 to 1.25. The void area may be defined by a plurality of holes, wherein each of the holes of the plurality of holes has a diameter from 1 mm to 20 mm. The solid area may have a raised portion that is conical-shape. The raised portion may be rigidly affixed to the distributor plate. The distributor plate may have a diameter ranging from 10 cm to 290 cm, preferably from 20 cm to 100 cm. The distributor plate may have a thickness from 5 to 20 mm, preferably from 10 to 18 mm. The distributor plate may provide for a uniform linear velocity of the ternary gas mixture in the reactor vessel, wherein the uniform linear velocity may vary by ±5% of mean linear velocity. The solid area may be defined by one or more removable devices inserted in at least a portion of the plurality holes, so that the distributor plate has a void area that is from 50% to 80% of the total area of the distributor plate. The removable devices may be selected from the group consisting of bolts, rivets, threaded inserts, forged hardware, or combinations thereof.

[0012] A fourth embodiment of the present invention is directed to a process for producing hydrogen cyanide, comprising providing a ternary gas mixture comprises at least 25 vol.% oxygen; passing at least a portion of the ternary gas mixture through a distributor plate to form an evenly distributed gas mixture, wherein the distributor plate is disposed within the reactor vessel downstream of the inlet port, the distributor plate having a diameter that is greater than the inlet port and less than a maximum internal diameter of the reactor vessel, wherein the distributor plate has a void area that is from 50% to 80% of the total area of the distributor plate and wherein the distributor plate comprises a solid area that is aligned with a centerpoint of the inlet port; contacting the evenly distributed gas mixture with a catalyst in the reactor vessel to provide a reaction product comprising hydrogen cyanide; and recovering the hydrogen cyanide from at least one outlet port of the reactor, wherein the evenly distributed gas mixture has a coefficient of variation that is less than 0.1 across the diameter of the catalyst bed.

[0013] A fifth embodiment of the present invention is directed to a process for producing hydrogen cyanide, comprising providing a ternary gas mixture comprising a methane-containing gas, an ammonia-containing gas, and an oxygen-containing gas, to at least one inlet port of a reactor vessel; passing at least a portion of the ternary gas mixture through a distributor plate to form an evenly distributed gas mixture, wherein the distributor plate has a void area defined by a plurality of holes that is from 50% to 80% of the total area of the distributor plate and wherein the distributor plate comprises a solid area having raised portion that is conical-shape; contacting the evenly distributed gas mixture with a catalyst in the reactor vessel to provide a reaction product comprising hydrogen cyanide; and recovering the hydrogen cyanide from at least one outlet port of the reactor, wherein the evenly distributed gas mixture has a coefficient of variation that is less than 0.1 across the diameter of the catalyst bed.

[0014] A sixth embodiment of the present invention is directed to a process for producing hydrogen cyanide, comprising providing a ternary gas mixture comprises at least 25 vol.% oxygen; passing at least a portion of the ternary gas mixture through a distributor plate to form an evenly distributed gas mixture, wherein the distributor plate is disposed within the reactor vessel downstream of an inlet port, the distributor plate has a plurality of holes having a diameter from 1 mm to 20 mm and a solid area defined by one or more removable devices inserted in at least a portion of the plurality holes, so that the distributor plate has a void area that is from 50% to 80% of the total area of the distributor plate; contacting the evenly distributed gas mixture with a catalyst in the reactor vessel to provide a reaction product comprising hydrogen cyanide; and recovering the hydrogen cyanide from at least one outlet port of the reactor, wherein the evenly distributed gas mixture has a coefficient of variation that is less than 0.1 across the diameter of the catalyst bed. In one embodiment, the removable devices are selected from the group consisting of bolts, rivets, threaded inserts, forged hardware, or combinations thereof. In one embodiment, the solid area is aligned with a centerpoint of the inlet port. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a simplified schematic flow diagram of an HCN synthesis system according to an embodiment of the presently claimed invention.

[0016] FIG. 2 is top view of a distributor plate according to an embodiment of the presently claimed invention.

[0017] FIG. 3 A is a side view of a distributor plate having a conical shaped solid area according to an embodiment of the presently claimed invention.

[0018] FIG. 3B is a perspective view of a distributor plate in FIG. 3A.

[0019] FIG. 4 is a cross-section view of a reactor vessel according to an embodiment of the presently claimed invention.

DETAILED DESCRIPTION OF THE INVENTION

[0020] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, group of elements, components, and/or groups thereof.

[0021] Language such as "including," "comprising," "having," "containing," or "involving," and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, as well as equivalents, and additional subject matter not recited. Further, whenever a composition, a group of elements, process or method steps, or any other expression is preceded by the transitional phrase "comprising," "including," or "containing," it is understood that it is also contemplated herein the same composition, group of elements, process or method steps or any other expression with transitional phrases "consisting essentially of," "consisting of," or "selected from the group of consisting of," preceding the recitation of the composition, the group of elements, process or method steps or any other expression.

[0022] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims, if applicable, are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The embodiment was chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated. Accordingly, while the invention has been described in terms of embodiments, those of skill in the art will recognize that the invention can be practiced with modifications and in the spirit and scope of the appended claims.

[0023] Reference will now be made in detail to certain disclosed subject matter. While the disclosed subject matter will be described in conjunction with the enumerated claims, it will be understood that they are not intended to limit the disclosed subject matter to those claims. On the contrary, the disclosed subject matter is intended to cover all alternatives, modifications, and equivalents, which can be included within the scope of the presently disclosed subject matter as defined by the claims.

[0024] Hydrogen cyanide ("HCN") is produced on an industrial scale according to either the Andrussow process or by the BMA process. In the Andrussow process, methane, ammonia and oxygen-containing raw materials are reacted at temperatures above 1000°C in the presence of a catalyst to produce a crude hydrogen cyanide product comprising HCN, hydrogen, carbon monoxide, carbon dioxide, nitrogen, residual ammonia, residual methane, and water. The catalyst is typically a wire mesh platinum/rhodium alloy or a wire mesh platinum/iridium alloy. Other catalyst compositions can be used and include, but are not limited to, a platinum group metal, platinum group metal alloy, supported platinum group metal or supported platinum group metal alloy. Other catalyst configurations can also be used and include, but are not limited to, porous structures, wire gauze, tablets, pellets, monoliths, foams, impregnated coatings, and wash coatings.

[0025] Natural gas is typically used as the source of methane while air, oxygen-enriched air, or pure oxygen can be used as the source of oxygen. As would be understood by one of ordinary skill in the art, the source of the methane may vary and may be obtained from renewable sources such as landfills, farms, biogas from fermentation, or from fossil fuels such as natural gas, oil accompanying gases, coal gas, and gas hydrates as further described in VN Parmon, "Source of Methane for Sustainable Development", pages 273-284, and in Derouane, eds. Sustainable Strategies for the Upgrading of Natural Gas: Fundamentals, Challenges, and Opportunities (2003).

[ 00261 In general, FIG. 1 shows a HCN synthesis system 100. Generally, the HCN is produced in a convertor 102 comprising an elongated conduit 104 and a reactor vessel 106. In the Andrussow process, the reactant gases, which include an oxygen-containing gas feed stream 108, a methane-containing gas feed stream 110, and an ammonia-containing gas feed stream 112, are introduced into the elongated conduit 104. It is noted that the feed locations shown in FIG. 1 are schematic and is not intended to show an order for feeding the reactants to the elongated conduit 104. In some embodiments, methane-containing gas feed stream 110 and ammonia- containing gas feed stream 112 may be combined prior to being introduced to elongated conduit 104. In one embodiment, elongated conduit 104 may contain one or more static mixing zones having tabs for producing a thoroughly mixed ternary gas mixture 114. In one embodiment, the ternary gas mixture 114 comprises at least 25 vol.% oxygen. In some embodiments, the ternary gas mixture 114 may comprise at least 28 vol.% oxygen. Ternary gas mixture 114 exits elongated conduit 104 and contacts a catalyst contained within reactor vessel 106 to form a crude hydrogen cyanide product 116 containing HCN. The catalyst may be within a catalyst bed 118.

[0027] Prior to contacting the catalyst bed 118, ternary gas mixture 114 contacts a distributor plate 120. Distributor plate 120 functions as an impingement plate to break a jet flow of the ternary gas mixture entering reactor vessel 106. "Jet flow" refers to a flow of gas that concentrates in one location. Because the inlet to reactor vessel 106 is smaller than the diameter of reactor vessel 106, ternary gas mixture 114 is susceptible to jet flow. Jet flow creates nonuniform linear velocity that creates hot spots on the catalyst bed. Distributor plate 120 is spaced apart from the inlet port of reactor vessel 106 and is upstream of catalyst bed 118. Ternary gas mixture 114 enters reactor vessel 106 and has a jet flow that needs to be broken to avoid hot spots in catalyst bed 118. Advantageously, the present invention uses a distributor plate 120 that is suitable for breaking a jet flow of the ternary gas mixture 114, without a significant pressure drop across the distributor plate 120. This prevents a large pressure drop within reactor vessel 106. In some embodiments, distributor plate 120 may also be used to further mix ternary gas mixture 114 as needed. [0028] Reactor vessel 106 may also comprise a flame arrestor 122 positioned downstream of distributor plate 120, a radiation shield 124 adjacent to catalyst bed 118 and a catalyst support assembly 126 downstream of catalyst bed 118.

[0029] Flame arrestor 122, which is shown in the FIGS. 1 and 4, may comprise a bed of packing material or ceramic pills supported in a basket, and is spatially disposed upstream from the catalyst bed 118. Ceramic refractory materials such as ceramic pills, ceramic foams, ceramic fiber blankets, alumina-silica refractory, non-woven blankets, combinations thereof, and the like may be present in flame arrestor 122. While the size of the pills used in the pill bed can vary widely, the diameter of the pills is generally from 1 mm to 20 mm, e.g., 3 mm to 13 mm. In one embodiment, the depth of the pill bed is at least 0.4 m, e.g., at least 0.5 m. Nonlimiting examples of suitable ceramic refractory material compositions include at least 90 wt.% alumina, e.g., at least 95 wt.% alumina. Preferably flame arrestor 122 contains less than 10 wt.% silica, e.g., less than 6 wt.% silica. Flame arrestor 122 also enhances the mixing of ternary gas mixture 1 14 and produces a substantially uniform composition of ternary gas mixture 114 across catalyst bed 118. It should be noted that the use of the flame arrestor 122 substantially reduces the potential for the heated ternary gas mixture 114 to become detonable through transfer from deflagration to detonation.

[0030] Flame arrestor 122 may assist in evenly distributing the ternary gas across catalyst bed 118. The distributor plate 120 and flame arrestor 122 operate together to provide an evenly distiibuted ternary gas mixture. Advantageously, even distribution is achieved when the jet flow of ternary gas mixture 114 is broken by distributor plate 120. Without this, the linear velocity through flame arrestor 122 may be not uniform and the variations in linear velocity may cause burning creating hot spots or holes in the catalyst bed. This leads to further problems on the catalyst bed, including reduced HCN yield and ternary gas mixture bypass. Advantageously, by breaking the jet flow using distributor plate, a uniform linear velocity may be maintained in flame arrestor 122. In one aspect, the velocity through the catalyst bed is at least 2 m/s, e.g., at least 5 m/s or at least 7 m/s. Higher linear velocities may be used with increased production. For purposes of the present invention, breaking the jet flow reduces variation in the linear velocity and maintains a uniform linear velocity. Uniform linear velocity varies by ±5% between any two points in the reactor vessel 106. [0031] Reactor vessel 106 may also comprise a heat exchanger 128, e.g., waste heat boiler, for cooling crude hydrogen cyanide product 116. Although not shown in FIGS. 1 or 4, it is preferred for flame arrestor 122, radiation shield 124, and catalyst support assembly 126 to abut the internal wall of reactor vessel 106 to prevent bypass of ternary gas mixture. In other words, the cross-sectional planar area of flame arrestor 122, radiation shield 124, and catalyst support assembly 126 is larger than the area of distributor plate 120.

[0032] Ammonia can be recovered from crude hydrogen cyanide product 116 in an ammonia recovery section 130 and returned via line 132. The HCN can be further refined in an HCN refining section 134 to a purity required for the desired use. In some embodiments, the HCN may be a high purity containing less than 100 mpm water.

[0033] The reactant gases are supplied to an elongated conduit to provide a ternary gas mixture having a molar ratio of ammonia-to-oxygen from 1.2 to 1.6, e.g., from 1.3 to 1.5, a molar ratio of ammonia-to-methane from 1 to 1.5, e.g., from 1.1 to 1.45 and a molar ratio of methane-to-oxygen from 1 to 1.25, e.g., from 1.05 to 1.15. For example, a ternary gas mixture may have a molar ratio of ammonia-to-oxygen of 1.3 and methane-to-oxygen 1.2. In another exemplary embodiment, the ternary gas mixture may have a molar ratio of ammonia-to-oxygen of 1.5 and methane-to-oxygen of 1.15. The oxygen concentration in the ternary gas mixture may vary depending on these molar ratios. In one embodiment, the ternary gas comprises at least 25 vol.% oxygen, e.g., at least 28 vol.% oxygen. In some embodiments, the ternary gas mixture comprises from 25 to 32 vol.% oxygen, e.g., from 26 to 30 vol.% oxygen. Various control systems may be used to regulate the reactant gas flow. For example, flow meters that measure the flow rate, temperature, and pressure of the reactant gas feed streams and allow a control system to provide "real time" feedback of pressure- and temperature-compensated flow rates to operators and/or control devices may be used.

[0034] As will be appreciated by one skilled in the art, the foregoing functions and/or process may be embodied as a system, method or computer program product. For example, the functions and/or process may be implemented as computer-executable program instructions recorded in a computer-readable storage device that, when retrieved and executed by a computer processor, controls the computing system to perform the functions and/or process of embodiments described herein. In embodiments, the computer system can include one or more central processing units, computer memories (e.g., read-only memory, random access memory), and data storage devices (e.g., a hard disk drive). The computer-executable instructions can be encoded using any suitable computer programming language (e.g., C++, JAVA, etc.). Accordingly, aspects of the present invention may take the form of an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects.

[0035] In one embodiment, the ternary gas mixture that enters reactor vessel 106 is thoroughly mixed and has a coefficient of variation (CoV) that is less than 0.1 across the diameter of the catalyst bed, or more preferably less than 0.05 and even more preferably of less than 0.01. In terms of ranges, the CoV may be from 0.001 to 0.1, or more preferably from 0.001 to 0.05. CoV is defined as the ratio of the standard deviation, σ, to the mean, μ. Ideally, CoV would be a low as possible, for example less than 0.1, for example, 0.05. The HCN unit may operate above a CoV of 0.1, and CoV of 0.2 is not unusual, i.e. ranging from 0.01 to 0.2 or from 0.02 to 0.15, but above 0.1 the operating cost is higher and HCN yield is lower, for example 2% to 7% lower, translating into a lost opportunity of millions of dollars per year in continuous commercial operation. The distributor plate maintains the low CoV achieved in the mixer to allow the reactor and process to achieve higher HCN yields to improve operating performance.

[0036] In general, as the ternary gas mixture is distributed, the pressure drop in the convertor and in particular in the reactor vessel would be expected to increase. This may be especially true for complex distributor plates and for multiple distributor plates. Minimizing the pressure drop may reduce the maximum pressure of the ternary gas mixture and thus reduce potential pressure in the event of a detonation. To assist in distribution, the jet flow is broken. A substantially evenly distributed ternary gas may achieve substantial uniformity in mean velocities and/or temperatures across the reactor bed and avoids hot spots on the catalyst bed. In one embodiment, the pressure drop in reactor vessel 106 is less than 150 kPa, e.g., from 35 to 125 kPa. Unless otherwise indicated as gauge, all pressure are absolute. Smaller pressures drops are preferred.

[0037] FIG. 2 is top view of the upstream surface of a distributor plate 120 that breaks a jet flow to provide a uniform linear velocity, i.e. within ±5% of mean linear velocity, across the reactor bed without a high pressure drop. As shown, distributor plate 120 is substantially circular, but in other embodiments any suitable shape, such as rectangular, square, oval, ellipse, triangle, or other polygonal shapes that corresponds to the shape of the reactor vessel may be used. In one embodiment, distributor plate 120 has a diameter that is greater than the inlet port and less than a maximum internal diameter of reactor vessel 106. The inlet port has an internal diameter that may be similar to the mixing vessel and is generally from 5 to 60 cm, e.g., from 10 to 35 cm. The internal diameter of reactor vessel 106 may vary depending on the commercial unit, and may range from 50 to 300 cm, e.g. from 75 to 200 cm. An exemplary distributor plate may have a diameter ranging from 10 cm to 290 cm, e.g., from 20 cm to 100 cm. In one embodiment, distributor plate 120 has a circumference 150 that does not contact the internal wall 148 of reactor vessel 106 as shown in FIG. 4, thereby leaving a circumferential opening for the ternary gas to pass around distributor plate 120. Distributor plate 120 may be aligned transversely to the flow of the ternary gas mixture entering the reactor vessel. Distributor plate 120 comprises a solid area 140 and plurality of holes 142 spaced apart by area 143. In one aspect, distributor plate 120 may be coated. In one aspect, distributor plate 120 may be substantially planar. In other embodiments, as shown in FIGS. 3 A and 3B, distributor plate 120 may have a raised conical-shape 141 in the solid area 140. The thickness of distributor plate 120 may be sufficient to support its own weight during operation and routine handling, and may vary as needed within reactor vessel 106. In one embodiment, distributor plate 120 may have a thickness from 5 to 20 mm, e.g., from 10 to 18 mm.

[0038] Solid area 140 may generally occupy the centerpoint of distributor plate 120, but is aligned with the centerpoint of the inlet port to the reactor vessel. In one preferred embodiment, solid area 140 may be concentrically aligned with the centerpoint of the inlet port to the reactor. Solid area 140 breaks up the jet flow of the ternary gas mixture to assist in evenly distributing the ternary gas mixture through and around distributor plate 120. In addition, solid area 140 may prevent a ternary gas mixture from creating hot spots in the catalyst bed.

[0039] Solid area 140 may have a shape that corresponds to the shape of distributor plate

120. In some embodiments, the shape of solid area 140 may be similar to the inlet port to the reactor. Solid area 140 may have a diameter approximate to or less than the diameter of the inlet port to the reactor. It should be understood that when solid area 140 is not substantially circular the term diameter may refer to the maximum internal diameter of the shape of solid area 140.

[0040] For purposes of the present invention, solid area 140 preferably has a diameter that is less than or equal to the diameter of distributor plate 120. The diameter (X) of distributor plate 120 and the diameter (y) of solid area 140 may satisfy the following relationship: 0.1 < < 0.7, e.g., 0.15 < < 0.6, 0.2 < ^ < 0.5, or more preferably 0.25 < < 0.35. This is the same

Λ^" A" A relationship regardless of whether solid area 140 is planar or raised. When the diameter of solid area 140 is too small, the jet flow of the ternary gas mixture may not be sufficient broken and, in addition, the ternary gas mixture may not be adequately distributed. Solid area 140 has an area that is less than 25%, e.g., less than 20%, of the total area of the distributor plate. Advantageously, this allows the distributor plate of the present invention to break the jet flow while still providing a ternary gas mixture with a low CoV of less than 0.1 across the diameter of the catalyst bed.

10041 J In one embodiment, solid area 140 may comprise no holes. Solid area 140 may be formed by filling holes in with a suitable material such as a welding material or a sheet of metal that is adhered to distributor plate 120. In some embodiments, bolts, rivets, threaded inserts, forged hardware, or other such removable devices may be placed in holes as needed to define solid area 140. This provides an adjustable solid area 140 that can be repositioned as needed to distribute the ternary gas mixture across the catalyst bed. In addition, the bolts, rivets, or other such removable devices may be replaced and cleaned as needed to remove any deposits on the surface of solid area or distributor plate.

10042] As shown in FIGS. 3A and 3B, solid area 140 may have a raised portion that is a conical shape 141. Raised portion may be solid or hollow. Conical shape 141 is rigidly affixed directly to distributor plate 120. As ternary gas mixture 114 enters head space 154, conical shape 141 deflects the mixture in advance of contacting distributor plate 120. Thus, conical shape 141 may also be referred to as a pre-diffuser. Conical shape 141 may occupy a portion or the entire solid area 140. In one embodiment, conical shape 141 may have height that is less than the radius of the distributor plate. Conical shape may be a right cone or an oblique cone. Conical shape may have a vertex that is pointed, rounded, squared, blunted, beveled, etc. A pointed knife-shape vertex may be preferred. The sides of conical shape may be smooth and gradually tapers to distributor plate 120. The pitch, or angle, of the conical shape's sides may be from 5° to 75°, e.g., from 10° to 60°. [0043] In optional embodiments, the raised portion in solid area 140 may have other shapes such as a pyramidal shape or a prism having multiple surfaces. Alternative conical shapes may be a cylinder or trapezoidal shape having a squared vertex or flat vertex.

[0044] The plurality of holes 142 defines a void area that is at least 50% to 80%, e.g., from 50%) to 75%, of the total area of distributor plate 120. The range of 50% to 80%> void area advantageously allows the present invention to achieve a low pressure drop of less than 1 kPa, e.g., less than 0.5 kPa, across the distributor plate 120. Thus, breaking the jet flow has a minimal impact on the overall pressure drop in reactor vessel 106. The number of holes 142 is not limited and may vary to achieve the desired void area. The pattern of holes may be concentric, aligned in rows, staggered, or in a lattice pattern such as a rhombic lattice, square lattice, hexagonal lattice, rectangular lattice, parallelogrammic lattice or equilateral lattice. For example, in a hexagonal lattice pattern, the theoretical limit for the void area is about 90%. The holes in the pattern may be spaced evenly. The holes 142 may be made in any suitable manner, e.g., drilled or punched out of distributor plate 120. Holes 142 may be an edge that is sharp, chamfered or radiused. An area 143 between holes may be planar. Each of the holes of the plurality of holes 142 may have a diameter from 1 mm to 20 mm, e.g., from 5 mm to 18 mm or from 12 to 15 mm. In one embodiment, each hole may have a similar diameter. When different sized holes are used, the larger holes may be near the outer circumference of distributor plate 120. The area 143 between holes may be substantially planar. In one embodiment, machining or polishing the distributor plate to a surface roughness (rms) of about 125 microinches (3.2 micrometers).

[0045] In one embodiment, the walls of holes 142 through distributor plate 120 may be substantially parallel to allow the ternary gas mixture to pass through and may assist in evenly distributing the ternary gas mixture across the catalyst bed. Optionally, the walls may be tapered from the upstream surface to downstream surface or downstream surface to upstream surface at an angle from 5° to 60°.

[0046] As shown in FIG. 4, distributor plate 120 is disposed within the reactor vessel 106 downstream of the inlet 144 and upstream of the flame arrestor 122 and catalyst bed 118. Distributor plate 120 may be in the head space 154 so that distributor plate 120 is spaced apart from inlet 144 and flame arrestor 122 by one or more arm braces 146. In one embodiment, distributor plate 120 is spaced away from the inlet so that circumferential opening 152 is equal to or greater than the inlet area. One or more arm braces 146 are connected to the downstream surface of distributor plate 120 and mounted to sidewalls 148 of reactor vessel 106. The number of arm braces 146 may vary from one to ten, e.g., from three to eight.

[0047] In a preferred embodiment, distributor plate 120 may be welded, e.g., tack- welded, to the arm braces 146 and to the inside the surface of reactor vessel 106. This provides for an circumferential opening 152. In optional embodiments, distributor plate 120 may be slip-fit to the inside surface of reactor vessel 106 or may rest upon an annular support ring.

[0048] Conical shape 141 shown in FIG. 4 is aligned with a centerpoint of inlet 144, preferably concentrically aligned. Distributor plate 120 may also be aligned with the centerpoint of inlet 144.

[0049] Perimeter 150 of distributor plate 120 may be rounded or squared. Perimeter 150 does not contact sidewall 148 and defines a circumferential opening 152 between sidewalls 148 and distributor plate 120, As ternary gas mixture 114 is distributed through and around distributor plate 120, the ternary gas mixture may flow through circumferential opening 152. In one embodiment, the circumferential opening 152 may have an area that is equal to or greater than the total area of distributor plate 120. Thus, circumferential opening 152 may have an area that is greater than void area, e.g., at least two or three times larger. This may allow a majority of the ternary gas mixture to pass around distributor plate 120.

[0050] To provide a low pressure drop in reactor vessel 106, it is necessary to reduce the total surface area of distributor plate 120 by having fewer plates. One distributor plate 120 is sufficient to break the jet flow. Thus, it is preferred to have one distributor plate 120 in reactor vessel 106, but more plates can be used when the surface area of the distributor plates does not increase the pressure drop.

[0051] The deflagration or risk and impact of a detonation under adverse operating conditions should also be avoided in the convertor, and in particular in the reactor vessel. The term "deflagration" as used herein refers to a combustion wave propagating at subsonic velocity relative to the unburned gas immediately ahead of the flame. "Detonation" refers to a combustion wave propagating at supersonic velocity relative to the unburned gas immediately ahead of the flame. Deflagrations typically result in modest pressure rise whereas detonations can lead to extraordinary pressure rise. The present invention provides an advantageous solution to achieve even distribution of a ternary gas mixture across a catalyst bed by breaking the jet flow while minimizing the pressure drop in the reactor vessel. 10052 J The materials of construction for distributor plate 120 may vary and can be any material compatible with the ternary gas mixture, capable of withstanding design temperatures and pressures in the reactor vessel without significant degradation, and that does not promote reaction of the gases in the ternary gas mixture prior to the catalyst bed. In one embodiment, the distributor plate may be constructed of stainless steel materials of construction including, but not limited to, 31 OSS, 316SS, and 316L.

[0053] A flame arrestor 122 is spatially disposed above catalyst bed 118 so as to provide a space there between. The flame arrestor quenches any upstream burning resulting from flash back within the reaction vessel. Distributor plate 120 may prevent a jet flow from burning through flame arrestor 122. Ceramic foam may be disposed along at least a portion of an interior wall of the housing defining the internal reaction chamber and the catalyst. The ceramic foam minimizes feed gas bypass due to catalyst shrinkage when the reactor is shut down. Ceramic foam disposed above the catalyst bed functions to minimize ternary gas volume, reduce pressure drop and quench formation of radicals during operation of the reactor. Ferrules are disposed in each of the outlets of the housing and provide fluid communication between the catalyst bed and an upper portion of a waste heat boiler. An undersupport having a substantially honeycomb configuration to reduce pressure drop across the undersupport is disposed substantially adjacent a lower surface of the catalyst bed.

[0054] The reaction to produce HCN is conducted in catalyst bed 118. Suitable catalysts for use in catalyst bed 118 of the Andrussow process contain Group VIII metals. The Group VIII metals include platinum, rhodium, iridium, palladium, osmium or ruthenium and the catalyst can be such metals, a mixture of such metals or alloys of two or more of such metals. A catalyst containing from 50 wt.% to 100 wt.% platinum, based on the total weight of the catalyst, is employed in many instances for the production of HCN. However, a metal, mixture or alloy containing at least 85 wt.% platinum and up to 15 wt.% rhodium or at least 90 wt.% platinum and up to 10 wt.% rhodium, based on the total weight of the catalyst, is often the preferred catalyst.

[0055] Catalyst bed 118 may be in the form of one or more layers of wire mesh, gauze, or other packed or oriented structure suitable for conducting the reaction, such as a corrugated structure. In an exemplary embodiment, catalyst bed 118 is in the form of woven gauze layers having various mesh sizes. The number of layers of gauze and the mesh size and wire diameter can be varied depending on the specific operating parameters of the process. Generally, however, when employing a plurality of layers of mesh gauze as catalyst bed 118, the mesh gauze is provided with a mesh size from 16 to 31 openings per linear cm and with wire diameter from 0.076 mm to 0.228 mm.

[0056] An igniter hole 160 extends through radiation shield 124. Igniter hole 160 enables an igniter to touch the upper surface of catalyst bed 1 18 and ignite catalyst bed 118. Other ignition techniques are available that do not require a hole in radiation shield 124. The ignition of catalyst bed 118 will be described in detail hereinafter.

[0057] Additional layers of material such as gauze are placed at the bottom of igniter hole 160 to increase the pressure drop in the igniter hole area so as to equalize pressure drop across the diameter of catalyst bed 118. Catalyst bed 118 is thus provided with a substantially uniform pressure drop across the entire surface and structure of catalyst bed 118. That is, the width of the portion of catalyst bed 1 18 below igniter hole 160 (i.e., the additional layers of material) is substantially equal to the width of ignition hole 160. Although the additional layers of material have been referred to herein as "gauze", it should be understood that the material can be of any type of material that increases uniformity of the velocity profile across a cross-section perpendicular to the flow direction of the gaseous reactants through convertor 102. For example, if catalyst bed 118 is formed of pills, the additional layers of material may also be formed of pills, sheets of materials, gauze or any combinations of like or similar materials.

[0058] Returning to elongated conduit 104, there may be one or more mixers (not shown) for mixing the reactant gases to form ternary gas mixture 114. The mixers are shaped and sized so as to be able to thoroughly and quickly mix the reactant gases. The mixers may be any mixer that functions in the manner described herein. Nonlimiting examples of mixers which may be employed in the practice of the present invention are binary mixers, ternary mixers, bustle mixers, static mixers, and the like. The dimensions of the mixers can vary widely and will be dependent, to a large degree, on the capacity of reactor vessel 106.

[0059] In one embodiment, substantially uniform mixtures are provided using a vortex- generating tab mixer. VORTAB® is a suitable passive mixing element which is used in high- efficiency static mixers available from Chemineer, Inc. as part of the HEV (high efficiency vortex) product line. Generally, HEV mixers comprise trapezoidal tabs mounted at an angle to a mixer housing and generating tip vortices with alternating rotations to mix a passing fluid stream with minimal pressure loss while maintaining a relatively flat velocity profile associated with turbulent flow.

[0060] In one embodiment, the mixers may comprise static mixing zones having one or more rows, each row having one or more tabs that are suitable for creating vortices that mix the reactant gas(s). The tabs may be square or rectangular shaped. To avoid any additional pressure drop, the mixers should achieve thorough mixing at a pressure drop of less than 150 kPa in the elongated conduit, e.g., less than 125 kPa or less than 35 kPa.

[0061] A thoroughly mixed ternary gas for the purposes of the present invention has a CoV that is less than 0.1 across the diameter of the catalyst bed, or more preferably less than 0.05 and even more preferably of less than 0.01. In terms of ranges, the CoV may be from 0.001 to 0.1, or more preferably from 0.001 to 0.05. Low CoV beneficially increases the productivity of reactants being converted to HCN. A thoroughly mixed ternary gas advantageously increases the productivity of HCN and returns higher yields of HCN. When CoV exceeds 0.1, the reactant gases may be in concentrations that are outside the safe operating ranges for the catalyst bed. For example, when operating at higher oxygen concentrations in the ternary gas, a larger CoV may create an increase in oxygen that results in a flashback. In addition, when CoV is larger, the catalyst bed may be exposed to more methane, which may lead to a buildup of carbon deposits. The carbon deposits may decrease catalyst life and performance. Thus, there may be a higher raw material requirement with larger CoV.

[0062] In one embodiment, the mixer may also comprise an optional flow straightener (not shown). Optional flow straighteners may have a configuration to align the flow prior to the gas feed streams contacting a static mixing zone. Flow straighteners may also distribute the gas around the entire area of the conduit and substantially prevent the reactant gases from passing directly down the middle of conduit. Flow straighteners, when used, may be positioned proximal to each inlet port and distal to the static mixer(s).

[0063] Using a high oxygen concentration in the oxygen-containing source (i.e., low concentration of inerts such as nitrogen) offers the opportunity to reduce the size and operating cost of downstream equipment that would otherwise be necessary to process a large volume of inert nitrogen. In one embodiment, oxygen-containing gas comprises greater than 21 vol.% oxygen, e.g. greater than 28 vol.% oxygen, greater than 80 vol.%, greater than 90 vol.%, greater than 95 vol.% or greater than 99 vol.% oxygen. For purposes of clarity herein, whenever the term "oxygen-enriched air" is used, the term is intended to encompass an oxygen content of greater than 21 vol.% up to and including 100 vol.%, i.e., pure oxygen. Whenever the term "oxygen-containing gas feed stream" is used, the term is intended to encompass an oxygen content of 21 vol.% up to and including 100 vol.%, i.e., pure oxygen. Because oxygen- containing gas feed stream or pure oxygen is used it would have less containments than air and thus holes in distributor plate would be less likely to plug.

[0064] From the above description, it is clear that the present invention is well adapted to carry out the objects and to attain the advantages mentioned herein as well as those inherent in the presently provided disclosure. While preferred embodiments of the present invention have been described for purposes of this disclosure, it will be understood that changes may be made which will readily suggest themselves to those skilled in the art and which are accomplished within the spirit of the present invention.

[0065] The invention can be further understood by reference to the following examples.

Example 1

[0066] As illustrated in FIG. 4, a distributor plate having a plurality of holes to define a void area of 70% is placed in the head space of a reactor vessel having an inside diameter of 137.16 cm (54 inches). The distributor plate is placed near the overhead inlet, which has an internal diameter of 22.86 cm (9 inches). Distributor plate is constructed of 31 OSS and has a thickness of 9.53 mm (3/8 inch). Each hole has an average diameter of 11.11 mm (7/16 inch). The distributor plate is held by a plurality of arms that are welded to the internal wall of reactor vessel to align the distributor plate and to provide a circumferential area that is larger than distributor plate. The distributor plate has a solid area concentrically aligned with the inlet to the reactor vessel and contains a raised portion. The solid area is less than 25% of the total area of the distributor plate. The raised portion is a conical shape.

[0067] Reactant gases are introduced to a mixing zone that feeds an overhead inlet. Pure oxygen is used as the oxygen-containing gas. The reactant gases are fed at a methane-to-oxygen molar ratio of 1 :1.2 and an ammonia-to-oxygen molar ratio of 1 :1.5 to produce a ternary gas mixture containing approximately 28.5 vol.% oxygen. The mixing vessel thoroughly mixes the reactant gases to achieve a ternary gas mixture having a coefficient of variation (CoV) across the diameter of the catalyst bed of less than 0.1. The ternary gas mixture is introduced into the reactor vessel at an average linear gas velocity of 7 m/s. Once the jet flow of the ternary gas mixture is broken, the ternary gas mixture is further distributed by passing through a flame arrestor containing a basket of ceramic pills. The flame arrestor further distributes the ternary gas mixture prior to contacting the catalyst bed. Under Andrussow process reaction conditions, the pressure drop across the distributor plate is less than 1 kPa. The distributor plate breaks the jet flow of the ternary gas and provides a uniform linear velocity through the flame arrestor and catalyst bed. Thus, no hot spots are formed. In breaking the jet flow, the distributor plate maintains the CoV of less than 0.1 achieved by the mixing vessel.

Comparative Example A

[0068] In the head space of a reactor vessel of Example 1, no distributor plates are inserted. At an average linear gas velocity through the reactor of at least 7 m/s, the ternary gas mixture forms a gas jet. When the jet flow contacts the upper surface of the catalyst, the jet flow has a diameter from 22.86 to 25.4 cm (9 to 10 inches), which is similar to the internal diameter of the overhead inlet. This indicates that the gas jet is not distributed across the surface of the catalyst and may create hot spots on the catalyst bed and flame arrestor. The CoV is observed to be 0.2. HCN yield is 7%, less than that of Example 1 which has a distributor plate.

Comparative Example B

[0069] In the head space of a reactor vessel, multiple plates are inserted. The multiple plates have a series of holes. At least one of the plates is non-planar. Under the same conditions as Example 1, the ternary gas mixture from Example 1 is fed into the reactor and the pressure drop in the reactor vessel is greater than 150 kPa.

Comparative Example C

[0070] HCN is formed using the traditional reactor described in Example 1 of US Pat. No. 8,133,458, which has no distributor plate or radiation protection and where the catalyst support is simple with no expansion possibilities for the catalyst support. Further, the heat is removed by direct quenching of water to the hot reacted gases. The running of the catalyst is done with 12 vol.% ammonia, 13 vol.% natural gas, 75 vol.% air, a pressure of 4 bar, a specific catalyst load of 25 tN/m2d, and 16 catalyst gauzes 90/10 Pt/Rh at 1024 meshes with a wire diameter of 0.076 mm. The measured temperature in the catalyst is 1050°C.

[0071] The campaign length is 70 days with an efficiency of 50-55% (conversion of ammonia to HCN). As reported in US Pat. No. 8,133,458, the campaign is aborted due to cracks in the catalyst. Example 2

[0072] A distributor plate having a conical center section of Example 1 is installed in the reactor of Example 1. The catalyst support is otherwise the same as in Comparative Example C and the reactor is run at the same conditions. The campaign length is 100 days with an efficiency of 60-65%. No wrinkles or cracks are observed in the knitted catalyst pack, and CoV over the run averages from 0.05 to 0.1. An HCN yield improvement of approximately 7% is observed versus Comparative Example C.

Claims

We claim:

1. A process for producing hydrogen cyanide, comprising:

providing a ternary gas mixture comprising a methane-containing gas, an ammonia- containing gas, and an oxygen-containing gas, to at least one inlet port of a reactor vessel;

passing at least a portion of the ternary gas mixture around and through a distributor plate to break a jet flow of the ternary gas mixture, wherein the distributor plate is disposed within the reactor vessel downstream of the inlet port, the distributor plate having a diameter that is greater than the inlet port and less than a maximum internal diameter of the reactor vessel, wherein the distributor plate has a void area that is from 50% to 80% of the total area of the distributor plate, preferably from 60%> to 70%, and wherein the distributor plate comprises a solid area that is aligned with a centerpoint of the inlet port;

contacting the ternary gas mixture with a catalyst bed in the reactor vessel to provide a reaction product comprising hydrogen cyanide; and

recovering the hydrogen cyanide from at least one outlet port of the reactor.

2. The process of claim 1, wherein the reactor vessel further comprises a flame arrestor that is downstream of the distributor plate, wherein the flame arrestor comprises a refractory ceramic material.

3. The process of any of the preceding claims, wherein the ternary gas mixture has a coefficient of variation that is less than 0.1 across the diameter of the catalyst bed, preferably less than 0.05 across the diameter of the catalyst bed.

4. The process of any of the preceding claims, wherein the pressure drop in the reactor vessel is less than 150 kPa.

5. The process of any of the preceding claims, wherein the ternary gas mixture comprises at least 25 vol.% oxygen.

6. The process of any of the preceding claims, wherein the oxygen-containing gas comprises at least 80 vol.% oxygen.

7. The process of any of the preceding claims, wherein the ternary gas mixture has a molar ratio of ammonia-to-oxygen from 1.2 to 1.6 and a molar ratio of methane-to-oxygen from 1 to 1.25.

8. The process of any of the preceding claims, wherein the void area is defined by a plurality of holes, wherein each of the holes of the plurality of holes has a diameter from 1 mm to 20 mm.

9. The process of any of the preceding claims, wherein the solid area has a raised portion that is conical-shape.

10. The process of claim 9, wherein the raised portion is rigidly affixed to the distributor plate.

11. The process of any of the preceding claims, wherein the distributor plate has a diameter ranging from 10 cm to 290 cm, preferably from 20 cm to 100 cm.

12. The process of any of the preceding claims, wherein the distributor plate has a thickness from 5 to 20 mm, preferably from 10 to 18 mm.

13. The process of any of the preceding claims, wherein the distributor plate provides for a uniform linear velocity of the ternary gas mixture in the reactor vessel, wherein the unifonn linear velocity varies by ±5% of mean linear velocity.

14. The process of any of the preceding claims, wherein the solid area is defined by one or more removable devices inserted in at least a portion of the plurality holes, so that the distributor plate has a void area that is from 50% to 80% of the total area of the distributor plate

15. The process of claim 14, wherein the removable devices are selected from the group consisting of bolts, rivets, threaded inserts, forged hardware, or combinations thereof.