201121933 六、發明說明： 【發明所屬之技術領域】 本發明係關於自粗製曱醇製造二甲醚之方法。特定言 之，本發明係關於一種用於藉由催化脫水呈氣相形式之粗 製曱醇而製造二曱醚之方法，及一種原料，利用該原料可 確保根據本發明之方法長期穩定運行。此外，本發明係關 於一種用於執行根據本發明之方法的設備。 【先前技術】 多年來已知藉由催化脫水而自曱醇催化製造二曱醚 (DME)。美國專利US 2,014,408(例如）描述一種在諸如氧化 鋁、氧化鈦及氧化鋇之催化劑上，以350至400°C之溫度為 較佳，由甲醇製造DME及其純化之方法。 二甲醚製造之先前技術與目前實施之其他資訊可見於 Ullmann’s Encyclopedia of Industrial Chemistry，第六版， 1998 Electronic Release，關鍵字「dimethyl ether」中。在 第3章「Production」中，特定言之闡釋在固定床反應器中 進行氣態純曱醇之催化轉化，兩階段冷凝後，接著蒸餾反 應產物，其中自曱醇-水混合物分離DME產物。然後於另 一塔中分離曱醇-水混合物，其中自該製程採出水並將甲 醇再循環至DME反應器中。 應強調目前工業操作法包括利用純甲醇製造DME，如由 Vishwanathan 等人之 Applied Catalysis A: General 276 (2004) 25 1-255所闡釋。該文之純曱醇咸了解係純淨之基 本上無水之曱醇合成產物。另一方面，甲醇合成之直接產 151370.doc 201121933 物稱為粗製曱醇及除若干重量％水以外，亦含有各呈微量 存在之較高碳數醇、醚、酯、酮、醛、烴及溶解之合成氣 體成份（Ullmann’s Encyclopedia of Industrial Chemistry, 第六版，1998 Electronic Release，關鍵字「Methanol」， 第 4.1.3章「Byproducts」）。 由甲醇合成之直接產物（粗製甲醇）製造純甲醇時，一般 係採用多階段蒸餾或精餾法，其中在第一步中，於所謂之 低沸物塔中，沸點低於甲醇之成份係呈塔頂產物之形式分 離；亦就溶解氣體之移除而言，此中間產物稱為安定粗製 曱醇。有時，亦先開始蒸餾部份分離水，其中得到之曱醇 產物仍稱為粗製甲醇。隨後，在至少再一次蒸餾中，以塔 頂產物之形式獲得基本無水之純甲醇（Ullmann's Encyclopedia of Industrial Chemistry，第六版，1998 Electronic Release,關鍵 字「Methanol」，第5.4 章「Distillation ofCrude Methanol」）〇 由粗製甲醇製造純甲醇之過程涉及設備及能量之極高花 費，此因在甲醇純化塔中，須自較少量之高沸點水中分離 大量低沸點曱醇之故。為了讓純曱醇繼續用於隨後製造 DME，此點成為經濟負擔，因為必需再次完全蒸發甲醇。 ' 因此，長期以來存在仍舊需要提供一種由粗製甲醇製造 - DME之實際上有用之製程。例如未經審查之德國專利申請 案DE 3817816 A1主張及教示一種已整合之甲醇合成法， 由甲醇使用脫水催化劑，進行催化性製造DME之方法，其 特徵為在脫水反應器中，使來自甲醇合成反應器之混合物 於適宜催化劑（較佳為γ-Α1203)上至少部份反應，以回收 151370.doc 201121933 . DME，而無需先分離未反應之合成氣體且不需純化所產生 之甲醇。 美國專利說明書US 6,740,783 述-種用於自粗製甲 醇製造DME之方法。本文中，闡釋當使用常用之基於礬土 的脫水催化劑時，催化劑之活性會因粗製甲醇中之水含量 而削弱H解決方案，提議使用疏水性彿石作為脫水 催化劑，其在水存在下失活不太強烈。此外，水與沸石催 化劑之強路易斯酸性中心之結合會抑制催化劑之碳化。 美國專利申請案US 2009/0023958 A1中發明者作出相似 方法。再次，本發明之潛在目的係提供一種用於催化脫水 呈氣相之粗製甲醇的方法。根據本發明者’首先使粗製甲 醇進料流通過摻金屬之疏水性沸石催化劑，然後通過選自201121933 VI. Description of the Invention: TECHNICAL FIELD OF THE INVENTION The present invention relates to a process for producing dimethyl ether from crude decyl alcohol. In particular, the present invention relates to a process for producing diterpene ether by catalytic dehydration in the form of a crude gas in the form of a gas phase, and a raw material which ensures long-term stable operation of the process according to the present invention. Furthermore, the invention relates to an apparatus for performing the method according to the invention. [Prior Art] Dioxyl ether (DME) has been known to be catalyzed by decyl alcohol by catalytic dehydration for many years. U.S. Patent No. 2,014,408, for example, describes a process for the manufacture of DME from methanol and its purification on a catalyst such as alumina, titania and cerium oxide at a temperature of from 350 to 400 °C. Additional information on prior art and current practice of dimethyl ether production can be found in Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 1998 Electronic Release, keyword "dimethyl ether". In Chapter 3, "Production", it is specifically explained that the catalytic conversion of gaseous pure sterol is carried out in a fixed bed reactor, after two-stage condensation, followed by distillation of the reaction product, wherein the DME product is separated from the decyl alcohol-water mixture. The sterol-water mixture is then separated in another column where water is produced from the process and the methanol is recycled to the DME reactor. It should be emphasized that current industrial practices include the use of pure methanol to make DME as illustrated by Vishwanathan et al., Applied Catalysis A: General 276 (2004) 25 1-255. The pure sterols of this article are known to be pure anhydrous base sterol synthesis products. On the other hand, the direct production of methanol synthesis 151370.doc 201121933 is called crude sterol and in addition to several% by weight of water, it also contains a relatively high amount of alcohol, ether, ester, ketone, aldehyde, hydrocarbon and Dissolved synthesis gas composition (Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 1998 Electronic Release, keyword "Methanol", Chapter 4.1.3 "Byproducts"). When pure methanol is produced from a direct product of methanol synthesis (crude methanol), a multi-stage distillation or rectification method is generally employed, wherein in the first step, in the so-called low boiler column, the component having a boiling point lower than methanol is present. The form of the overhead product is separated; also in terms of the removal of dissolved gases, this intermediate product is referred to as diazepam crude sterol. Sometimes, some of the separated water is first distilled, and the decyl alcohol product obtained is still referred to as crude methanol. Subsequently, in at least one more distillation, substantially anhydrous pure methanol is obtained in the form of an overhead product (Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 1998 Electronic Release, keyword "Methanol", Chapter 5.4 "Distillation of Crude Methanol" The process of producing pure methanol from crude methanol involves an extremely high cost of equipment and energy, since a large amount of low-boiling sterols must be separated from a relatively small amount of high-boiling water in a methanol purification column. In order for the pure sterol to continue to be used in the subsequent manufacture of DME, this becomes an economic burden since it is necessary to completely evaporate the methanol again. Therefore, there is still a long-standing need to provide a process that is practically made from crude methanol - DME. For example, the unexamined German patent application DE 38 17 816 A1 teaches and teaches an integrated methanol synthesis process for the catalytic production of DME from methanol using a dehydration catalyst, characterized in that it is synthesized from methanol in a dehydration reactor. The reactor mixture is at least partially reacted on a suitable catalyst (preferably γ-Α1203) to recover 151370.doc 201121933 . DME without first separating the unreacted synthesis gas and without purifying the methanol produced. U.S. Patent Specification No. 6,740,783 describes a process for the manufacture of DME from crude methanol. In this paper, it is explained that when a conventional alumina-based dehydration catalyst is used, the activity of the catalyst is weakened by the water content in the crude methanol. The H solution is proposed, and it is proposed to use hydrophobic fossil as a dehydration catalyst, which is deactivated in the presence of water. Not too strong. In addition, the combination of water and the strong Lewis acid center of the zeolite catalyst inhibits carbonization of the catalyst. The inventors of U.S. Patent Application No. US 2009/0023958 A1 make a similar method. Again, a potential object of the present invention is to provide a process for the catalytic dehydration of crude methanol in the gas phase. According to the inventors' first, the crude methanol feed stream is passed through a metal-doped hydrophobic zeolite catalyst and then selected from
AhO3或SiOVAhO3之催化劑可解決此目的，其中脫水反應 係在絕熱反應器中進行。根據本發明者，此方法特徵組2 應有利於於反應胃中之溫度導引、畐,!產物之少量形成及^ 低催化劑失活。 總而言之，因此應注意：先前技術中已提出用於藉由催 化脫水呈氣相之粗製甲醇而製造二甲醚的各種方法或方法 變體，但所提出之方法在工業實踐中未得到認可。儘管以 上闡述相關先前技術，但現今藉由催化脫水呈氣相之甲醇 製造二甲趟之所有技術設備仍利用純甲醇作為進料進行操 作。不管所述之經濟優點，當使用純甲醇作為進料時，: 乎存在迄今仍無法解決之基本缺點。 【發明内容】 151370.doc 201121933 因此本發明之目的在於提供一種藉由催化脫水呈氣相之 粗製甲醇製造二甲醚之方法，其避免以上所提及之缺點且 適用於工業應用。 . 本發明藉由一種用於藉由催化脫水呈氣相之粗製甲醇製 • 造二甲醚之方法解決前面所提及之目的，其包括以下製程 步驟： (a) 自甲醇合成提供粗製曱醇， (b) 可在先前安定後及/或水之部分分離後蒸發粗製甲醇， 並調節反應溫度及反應壓力， (c) 以界定之空間速度將經蒸發之粗製甲醇裝料於裝填有 脫水催化劑之反應器中， (d) 排出包括二曱醚、未反應甲醇及水之氣態產物混合 物’ (e) 冷卻、部份冷凝及分離氣態產物混合物，其中得到作 為產物之氣態二甲醚以及液態水及曱醇，其中將甲醇再循 環至製程步驟1(a)，且其特徵在於用作原料之粗製甲醇中 以丙酮之質量當量計算之羰基化合物總含量不超過100 wt_ PPm，較佳不超過50 wt-ppm。 發現在藉由催化脫水呈氣相之粗製甲醇而製造二甲醚 •中’粗製甲醇中羰基化合物之含量對製程之長期穩定性具 決定重要性。此係令人驚奇的，此因迄今先前技術尚未論 及或甚至否定在自粗製曱醇製造DME之製程中含氧微量組 份對用於此目的之製造製程或設備性能的不利影響。例如 國際專利申請案WO 01/21561 A1教示經由中間產物DME由 151370.doc 201121933 甲醇製造短鏈烯烴中，諸如高級醇、醛或其他氧化化合物 之有機含氧微量組份的存在對反應的影響可忽略。與之相 比，現已發現當粗製甲醇原料中之羰基化合物的總含量超 出限值100 wt-ppm(以丙酮之質量當量計算）時，DME產物 中出現以不為所需的雜質形式之許多額外微量組份。此特 定言之用於粗製曱醇中僅包含丙酮作為羰基化合物之情 況。然而，當粗製曱醇原料亦含有較高，可能更具反應性 的羰基化合物，諸如甲基乙基酮（MEK)時，以粗製曱醇中 之羰基化合物的總含量不超過50 wt-ppm為較佳，此因已 觀察到當維持此已知極限值時，DME產物中出現可能具有 害性的微量組份之故。A catalyst of AhO3 or SiOVAhO3 can be used for this purpose, wherein the dehydration reaction is carried out in an adiabatic reactor. According to the present inventors, this method feature set 2 should facilitate the reaction of temperature in the stomach, the formation of a small amount of product, and the low catalyst deactivation. In summary, it should therefore be noted that various methods or process variants for the manufacture of dimethyl ether by catalytic dehydration of crude methanol in the gas phase have been proposed in the prior art, but the proposed method is not recognized in industrial practice. Although the related prior art is explained above, all of the technical equipment for producing dimethyl hydrazine by catalytic dehydration in the gaseous phase of methanol still operates with pure methanol as a feed. Regardless of the economic advantages described, when pure methanol is used as the feed, there are fundamental disadvantages that have not been solved to date. SUMMARY OF THE INVENTION 151370.doc 201121933 It is therefore an object of the present invention to provide a process for the manufacture of dimethyl ether from crude methanol which is subjected to catalytic dehydration in the gas phase, which avoids the disadvantages mentioned above and which is suitable for industrial applications. The present invention solves the aforementioned objects by a method for producing dimethyl ether by crude methanol in a gas phase by catalytic dehydration, which comprises the following process steps: (a) providing crude sterol from methanol synthesis (b) The crude methanol may be evaporated and the reaction temperature and reaction pressure may be adjusted after the previous stabilization and/or partial separation of the water, (c) the evaporated crude methanol is charged to the dehydrated catalyst at a defined space velocity. In the reactor, (d) discharging a gaseous product mixture comprising dioxane, unreacted methanol and water' (e) cooling, partially condensing and separating the gaseous product mixture, wherein gaseous dimethyl ether as a product and liquid water are obtained And decyl alcohol, wherein methanol is recycled to the process step 1 (a), and characterized in that the total content of the carbonyl compound in the crude methanol used as the raw material in terms of the mass equivalent of acetone does not exceed 100 wt_PPm, preferably does not exceed 50. Wt-ppm. It has been found that the production of dimethyl ether in crude methanol by catalytic dehydration in the gas phase • The content of the carbonyl compound in the medium crude methanol is of decisive importance for the long-term stability of the process. This is surprising because the prior art has not previously addressed or even negated the adverse effects of the oxygen-containing trace components on the manufacturing process or equipment performance for this purpose in the process of making DME from crude decyl alcohol. For example, International Patent Application No. WO 01/21561 A1 teaches the effect of the presence of an organic oxygen-containing microcomponent such as a higher alcohol, aldehyde or other oxidizing compound on the reaction of a short-chain olefin produced by the intermediate product DME from 151370.doc 201121933 methanol. ignore. In contrast, it has been found that when the total content of carbonyl compounds in the crude methanol feedstock exceeds the limit of 100 wt-ppm (calculated as the mass equivalent of acetone), many of the DME products appear in the form of undesirable impurities. Additional minor components. This is specifically the case where the crude sterol contains only acetone as a carbonyl compound. However, when the crude sterol starting material also contains a higher, possibly more reactive, carbonyl compound, such as methyl ethyl ketone (MEK), the total content of carbonyl compound in the crude decyl alcohol is not more than 50 wt-ppm. Preferably, it has been observed that when this known limit is maintained, a potentially harmful microcomponent may be present in the DME product.
亦已發現歸因於冷凝或聚合反應，此等微量組份形成導 致在設備内及/或在催化劑上形成沉積物之固體產物，致 使諸如熱交換器之設備區段的堵塞或催化劑之提前失活。 已於下.述相應實驗中觀察到此等沉積物。作為沉積物之重 要成份，可藉由分析測定鑒別六甲基苯（HMB)。以本身已 知之方式自曱醇與丙酮之反應可獲得相同結果，且歸因於 其165°C之高熔點可在較冷設備區段中形成固體沉積物並 導致催化劑之碳化。此反應係由Jayamani等人，Indian Journal of Chemistry, Section B: Organic Chemistry Including Medicinal Chemistry (1985)，24B(6)，687-9所述用於製備性製造 HMB。在 Journal of Catalysis，119, 288-299 (1989), Ganesan及 Pillai中亦描述甲醇與不同酮類及醛類在Al2〇3催化劑上之 反應，得到六曱基笨（HMB)，其中在350°C下丙酮與MEK 151370.doc 201121933 100%轉化且以87至90%得率得到HMB。機理上看出，反應 常經由無關於丙酮之羰基化合物進行以使丙酮為表示羰基 化合物總含量之適宜參照組份。此令人特別感興趣，此因 粗製甲醇含有此等化合物且ai2o3同樣係用作藉由氣相製 程製造DME之催化劑之故。因此，在丙酮參與及其他幾基 化合物存在下可發生非所需冷凝反應以得到諸如HMB之高 沸點化合物。然而，應考慮在Ganesan與Pillai論文中所述 之實驗中常使用約16 mol%之極高濃度羰基化合物，其顯 然高於粗製曱醇中之此等化合物之僅合計為數十至數百 ppm的常見濃度。 現已驚人地發現，藉由界定粗製甲醇中羰基化合物可容 許量之極限值，可維持DME製造設備之長期穩定操作且在 DME產物中不會檢測到達干擾濃度之雜質。已發現以丙酮 之質量當量計算之幾基化合物總含量不超過1 〇〇 wt-ppm， 副反應進行至不會負面影響設備操作與催化劑之次要程 度。此點特別適用於粗製甲醇中僅含有丙酮之情況。然 而，當粗製甲醇原料亦含有諸如甲基乙基酮（MEK)之較高 碳之可能更具反應性之羰基化合物時，粗製曱醇中以丙酮 之質量當量計算之幾基化合物總含量不超過50 wt-ppm較 佳，此因已觀察到當維持此極限值時，DME產物中不會出 現未知之可能有害的微量組份之故。因此，可針對確定作為 製造DME之原料之粗製甲醇來指定相應極限值，維持該值， 仍可能在不受干擾下操作設備，並得到夠純的DME產物。 藉由呈氣相之純曱醇之催化脫水法製造二曱醚時，該影 151370.doc 201121933 響不會出現，此因純曱醇中羰基化合物之總含量極低，其 中通常僅標示丙酮含量。例如，「AA級」純度級別之純曱 醇具有低於20 wt-ppm之丙酮含量（Supp, E” How to Produce Methanol from Coal，Springer Verlag, Berlin (1989)，134頁）。國 際甲醇製造商及消費者協會（International Methanol Producers and Consumers Association)之最新參照說明書指出丙酮極限 值為 30 mg/kg (2008年 1 月，http://www.impca.be/)。 據推斷，早期有關由呈氣相之粗製曱醇之催化脫水法製 造DME之論文尚未充分論述含氧有機微量組份之存在問 題，因為此等論文係關注粗製曱醇之水含量。在先前技術 中所述之許多實驗中，曾改用由純化學試劑曱醇與水混在 一起合成之粗製甲醇替代源自合成曱醇之技術設備的粗製 曱醇，以致無法發現以上所提及之問題。 美國專利說明書US 4,560,807提及除純甲醇以外，亦使 用包含較高量其他含氧物之不明確副產物曱醇用作製造 DME之原料的可能性。因此其中提及化合物甲基乙基醚、 曱酸曱酯與甲縮醛（二曱氧基甲烷）。 然而，説明僅關於此等雜質於DME產物中之預期積聚且 不關於其等對製造製程或對用於此目的之設備本身之性能 的可能有害作用。在包含於專利說明書之數字實例中，僅 再次使用純曱醇。 本發明之較佳態樣 尤佳地’將固定床反應器用作反應器。此類型反應器之 特徵為其結構簡單且已證明在由純曱醇產生DME之製造方 151370.doc •10· 201121933 面上相當成功。 本發明方法之有利態樣提供將γ_Α丨2〇3用作催化劑。其他 酸性固體催化劑亦可用於本發明方法中，但γ_Α12〇3具針對 其處理’其低毒性及經濟優點之一些優點。 在本發明之方法中，反應溫度較佳係處於2θθ與5 〇〇亡 間，尤佳250與450 C間。反應壓力較佳處於丨與1〇〇 bar(a) 間，尤佳1與30 bar(a)間。發現適宜空間速度為介於丨與8 kg/(kg.h)間，較佳介於丨與6 kg/(kg.h)間之值。界定空間速 度為每小時及每kg催化劑之甲醇kg數。 有利地，將經安定的粗製甲醇用作根據本發明方法之原 料。安定塔中溶解氣體含量之減小導致催化脫水呈氣相之 甲醇中更穩定之設備操作，此因在粗製甲醇導管或中間容 器中可避免除氣之故。此外，使潛在有害氣體成份避開脫 水催化劑。然而，粗製甲醇中具低含量之溶解氣體，最佳 將粗製甲醇用作原料而不預先安定。安定塔之省去可顯著 節省DME製造設備之投資費用。 根據本發明之較佳態樣’藉由蒸餾分離在製程步⑴⑷ 中獲得之包括二甲趟、水及未反應甲醇的產物混合物。可 應用常見的蒸顧、分館或精顧技術。分離後獲得之二甲醚 隨後可用作製造短鏈稀烴之原料，作為燃料及/或推進劑 或作為噴灑罐中之氣溶膠推進劑氣體。 本發明亦係關於-種適用作藉由以氣相形式催化脫水而 製造二甲謎之原料的粗製甲醇，其特徵為其具有總含量不 超過u)〇 較佳不超過50 wt_ppm之幾基化合物。 151370.doc ,, 201121933 若得=到所存賴的進一步資訊，但僅得到幾基化合物之 總含I作為總參數’則維持羰基化合物總含量之下限值不 超過50 wt-ppm更為安全。另一方面，若保證僅存在以可 檢測辰度之作爲幾基化合物之丙酮，則可使用不超過⑽ wt-PPm之羰基化合物總含量之上限值。 此外，本發明係關於一種用於進行根據本發明之方法的 设備。其包括用於進行根據專利申請範圍1(a)至⑷之製程 步驟的構件’特^言之用於提供自甲醇合成之粗製甲醇之 導管及/或接受罐’用於蒸發粗製甲醇及用於調節反應溫度 之熱交換器及/或加熱器’用於調節反應塵力之構件，用於 粗製甲醇之輸送構件，填充有脫水催化劑之反應器，用於 排出氣態產物混合物之導管，熱交換器及/或料冷卻產物 混合物之冷卻H，用於分離產物混合物之分離裝I，及在 脫水反應器前用於再循環未反應甲醇之導管。該設備之特 徵在於其操作如專财請範圍2之作為原料之粗製甲醇。 亦可自實施例及數字實狀以下描述獲得本發明之其他 發展’優點及可行應用。全部所述特徵自身或以任何組合 形成本發明’此與專利申請範圍中之其等内容或其等後面 引用無關。 【實施方式】 實施例 在催化曱醇合成設備中藉由低壓方法製造粗製甲醇並另 其供至安定塔中。扃史—+*—士 _ 在女疋硌中，進行粗製曱醇之蒸餾3 滩’其中將沸點低於甲典含夕知々、丨、丨w 於甲.之组份以塔頂產物形式分離。） 151370.doc •12· 201121933 以塔底產物形式獲得之經安定的粗製甲醇供至中間容器。 經安定的粗製甲醇之水含量係12重量％，其以丙酮計算之 %基化合物總含量係約50 wt_ppm，且丙酮含量係約3〇 ppm。藉由泵自中間容器採出粗製甲醇並利用熱交換器藉 由與脫水反應器之熱產物氣體間接熱交換而預加熱或部份 蒸發。在下游熱交換器中藉由與高壓蒸汽直接熱交換進行 最終瘵發及反應溫度之調節。藉由在脫水反應器之出口處 之壓力維持閥可調節反應壓力。使填充有塊狀丫_八12〇3催化 劑之DME反應器裝料粗製甲醇蒸氣，使反應器入口溫度為 300 C。曱醇空間速度係2.0 kg/(kg.h)，反應壓力係16 bar(a)。 由於脫水反應之相對低反應熱，故將DME&應器組態為絕 熱固定床反應器。在脫水反應器中，對應於依甲醇與水之 溫度及分壓的脫水反應之平衡，將粗製甲醇部份轉化為 DME與水。在此等條件下，達成之甲醇轉化率介於乃與以 重量％間；基於所用之曱醇，DME選擇率介於98與1〇〇 mol-C% 間。 將產物氣體排出脫水反應器並在熱交換器中藉由與採自 中間容器之較冷粗製甲醇間接熱交換而冷卻。在另一水冷 卻熱交換器中進行產物氣體之進一步冷卻，其中出現水及 未反應甲醇之部份冷凝。藉由兩階段蒸餾以本身已知之方 式（Ullmann's Encyclopedia of Industrial Chemistry，第六 版，1998 Electronic Release’ 關鍵字「Dimethyl Ether」， 第3章「Production」）進行產物之進一步處理，其中在第 一療潑階段中獲得以塔頂產物形式之DME。所得DME在下It has also been found that due to condensation or polymerization, the formation of such minor components results in the formation of solid products of deposits in the apparatus and/or on the catalyst, resulting in blockage of the equipment section such as heat exchangers or early loss of catalyst. live. These deposits have been observed in the corresponding experiments described below. As an important component of the deposit, hexamethylbenzene (HMB) can be identified by analytical determination. The same result can be obtained from the reaction of decyl alcohol with acetone in a manner known per se, and due to its high melting point of 165 ° C, solid deposits can be formed in the cooler equipment section and carbonization of the catalyst. This reaction was used for the preparative production of HMB as described by Jayamani et al., Indian Journal of Chemistry, Section B: Organic Chemistry Including Medicinal Chemistry (1985), 24B (6), 687-9. The reaction of methanol with different ketones and aldehydes on Al2〇3 catalysts is also described in Journal of Catalysis, 119, 288-299 (1989), Ganesan and Pillai, giving hexamethylene stupid (HMB) at 350°. Acetone and MEK 151370.doc 201121933 100% conversion and yielded HMB at 87 to 90% yield. It is shown in the mechanism that the reaction is often carried out via a carbonyl compound which is free of acetone so that acetone is a suitable reference component for indicating the total content of the carbonyl compound. This is of particular interest because the crude methanol contains these compounds and ai2o3 is also used as a catalyst for the manufacture of DME by a gas phase process. Thus, an undesired condensation reaction can occur in the presence of acetone and other base compounds to give high boiling compounds such as HMB. However, it should be considered that an extremely high concentration of carbonyl compound of about 16 mol% is often used in the experiments described in the paper by Ganesan and Pillai, which is clearly higher than the sum of these compounds in the crude sterols to only tens to hundreds of ppm. Common concentrations. It has now surprisingly been found that by defining the limits of the allowable amount of carbonyl compound in the crude methanol, long-term stable operation of the DME manufacturing equipment can be maintained and impurities reaching the interference concentration are not detected in the DME product. It has been found that the total amount of the base compound calculated in terms of the mass equivalent of acetone does not exceed 1 〇〇 wt-ppm, and the side reaction proceeds to a level that does not adversely affect the operation of the equipment and the catalyst. This is especially true when the crude methanol contains only acetone. However, when the crude methanol feedstock also contains a more reactive carbonyl compound such as methyl ethyl ketone (MEK), the total amount of the base compound in the crude sterol calculated as the mass equivalent of acetone does not exceed 50 wt-ppm is preferred because it has been observed that when this limit is maintained, no unknown potentially harmful minor components will be present in the DME product. Therefore, the corresponding limit value can be specified for determining the crude methanol as the raw material for the manufacture of DME. Maintaining this value, it is still possible to operate the apparatus without interference and obtain a pure DME product. When the diterpene ether is produced by catalytic dehydration of pure sterol in the gas phase, the shadow 151370.doc 201121933 does not occur, because the total content of carbonyl compounds in the pure sterol is extremely low, and usually only the acetone content is indicated. . For example, "AA grade" pure grade sterols have an acetone content of less than 20 wt-ppm (Supp, E" How to Produce Methanol from Coal, Springer Verlag, Berlin (1989), page 134). International Methanol Manufacturer The latest reference specification by the International Methanol Producers and Consumers Association indicates that the acetone limit is 30 mg/kg (January 2008, http://www.impca.be/). It is inferred that early The paper on the manufacture of DME by catalytic dehydration of crude sterols in the gas phase has not fully addressed the existence of oxygen-containing organic micro-components, as these papers focus on the water content of crude sterols. In many of the experiments described in the prior art. The crude sterol synthesized from the technical equipment of synthetic sterol was replaced by the crude methanol synthesized by the purification reagent sterol and water, so that the above-mentioned problems could not be found. US Patent Specification No. 4,560,807 In addition to pure methanol, it is also possible to use decyl alcohol, an undefined by-product containing a higher amount of other oxygenates, as a raw material for the manufacture of DME. Ethyl ethyl ether, decyl decanoate and methylal (dimethoxymethane). However, the description only relates to the expected accumulation of such impurities in the DME product and is not related to the manufacturing process or for this purpose. Possible detrimental effects of the performance of the device itself. In the numerical examples included in the patent specification, only pure decyl alcohol is used again. Preferred aspects of the invention are particularly preferred 'using a fixed bed reactor as the reactor. This type of reaction The device is characterized by its simple structure and has proven to be quite successful in the manufacture of DME from pure decyl alcohol 151370.doc •10·201121933. An advantageous aspect of the process of the invention provides for the use of γ_Α丨2〇3 as a catalyst. Other acidic solid catalysts can also be used in the process of the present invention, but γ_Α12〇3 has some advantages for its handling of its low toxicity and economic advantages. In the process of the present invention, the reaction temperature is preferably at 2θθ and 5 Between the 250 and 450 C. The reaction pressure is preferably between 丨 and 1〇〇bar(a), especially between 1 and 30 bar(a). The suitable space velocity is found to be between 丨 and 8 kg/( Between kg.h), preferably between With a value between 6 kg/(kg.h), the space velocity is defined as the number of kilograms of methanol per hour and per kg of catalyst. Advantageously, the stabilized crude methanol is used as a feedstock in the process according to the invention. The reduction in gas content results in a more stable equipment operation for catalytic dehydration in methanol in the gas phase, since degassing can be avoided in crude methanol conduits or intermediate vessels. In addition, the potentially harmful gas components are kept away from the dehydration catalyst. However, in the case of crude methanol having a low content of dissolved gas, it is preferred to use crude methanol as a raw material without pre-stabilization. The savings of the Anding Tower can significantly reduce the investment cost of DME manufacturing equipment. According to a preferred embodiment of the invention, the product mixture comprising dimethylhydrazine, water and unreacted methanol obtained in process step (1) (4) is separated by distillation. It can be applied to common steaming, branching or inspecting techniques. The dimethyl ether obtained after separation can then be used as a raw material for the manufacture of short-chain lean hydrocarbons as a fuel and/or propellant or as an aerosol propellant gas in a spray can. The present invention is also directed to a crude methanol which is useful as a raw material for the production of a dime by catalytic dehydration in a gas phase, which is characterized in that it has a compound having a total content of not more than u) 〇 preferably not more than 50 wt_ppm. . 151370.doc ,, 201121933 If it is further information on the remaining information, but only the total content I of the several base compounds is taken as the total parameter', it is safer to maintain the lower limit of the total content of the carbonyl compound not exceeding 50 wt-ppm. On the other hand, if it is ensured that only acetone having a detectable fraction as a base compound is present, an upper limit of the total content of the carbonyl compound of not more than (10) wt-PPm may be used. Furthermore, the invention relates to an apparatus for carrying out the method according to the invention. It comprises a component for carrying out the process steps according to the patent application scopes 1 (a) to (4), in particular, a conduit for the supply of crude methanol from methanol synthesis and/or a receiving tank for evaporating crude methanol and for a heat exchanger and/or a heater for adjusting the reaction temperature, a member for adjusting the reaction dust force, a conveying member for crude methanol, a reactor filled with a dehydration catalyst, a conduit for discharging a gaseous product mixture, a heat exchanger And/or cooling the product mixture to cool H, a separation unit I for separating the product mixture, and a conduit for recycling unreacted methanol prior to the dehydration reactor. The device is characterized by its operation as a crude methanol as a raw material in the range of 2 for the purpose of the operation. Other developments and possible applications of the present invention can also be obtained from the following examples and numerical examples. All of the described features are themselves or in any combination to form the present invention. This is not related to its content in the scope of the patent application or its subsequent references. [Embodiment] Example A crude methanol was produced by a low pressure method in a catalytic sterol synthesis apparatus and supplied to a stabilizer.扃史—+*—士_ In the son-in-law, the distillation of crude sterols is carried out. 3 The beaches have a boiling point lower than that of the Jiadian 含 々, 丨, 丨 甲. Separation. 151370.doc •12· 201121933 The stabilized crude methanol obtained as a bottom product is supplied to the intermediate vessel. The stabilized crude methanol has a water content of 12% by weight, a total base compound content of about 50 wt-ppm calculated as acetone, and an acetone content of about 3 〇 ppm. The crude methanol is withdrawn from the intermediate vessel by means of a pump and preheated or partially evaporated by means of a heat exchanger by indirect heat exchange with the hot product gas of the dehydration reactor. The final burst and the adjustment of the reaction temperature are carried out in the downstream heat exchanger by direct heat exchange with high pressure steam. The reaction pressure can be adjusted by a pressure maintaining valve at the outlet of the dehydration reactor. The DME reactor filled with bulk 丫_八12〇3 catalyst was charged with crude methanol vapor to bring the reactor inlet temperature to 300 C. The sterol space velocity is 2.0 kg/(kg.h) and the reaction pressure is 16 bar(a). Due to the relatively low heat of reaction of the dehydration reaction, the DME & configurator was configured as an adiabatic fixed bed reactor. In the dehydration reactor, the crude methanol fraction is converted to DME and water corresponding to the balance of the dehydration reaction of methanol and water at a temperature and partial pressure. Under these conditions, the methanol conversion achieved is between and minus %; based on the sterol used, the DME selectivity is between 98 and 1 〇〇 mol-C%. The product gas is discharged from the dehydration reactor and cooled in the heat exchanger by indirect heat exchange with the cooler crude methanol taken from the intermediate vessel. Further cooling of the product gas is carried out in another water-cooled heat exchanger in which partial condensation of water and unreacted methanol occurs. Further processing of the product by two-stage distillation in a manner known per se (Ullmann's Encyclopedia of Industrial Chemistry, Sixth Edition, 1998 Electronic Release 'keyword "Dimethyl Ether", Chapter 3 "Production"), wherein in the first treatment DME in the form of a top product is obtained in the pour phase. The resulting DME is under
S 151370.doc ,〇 201121933 游冷凝器中液化並因此自低沸物’例如微量氣體成份中分 離。以此方式，達到>99.9%之DME產物純度。在下游洗滌 器中’藉由將粗製曱醇用作洗務劑自仍存有之微量DME中 釋放出冷凝器之氣態塔頂產物。將載有DME之粗製甲醇以 原料再循環至脫水反應器。在第二蒸餾階段中，曱醇係以 塔頂產物之形式獲得，同樣將其以原料再循環至脫水反應 器。自製程去除以塔底產物形式獲得之廢水β 數字實例 為解釋羰基化合物總含量之極限值以更安全操作催化脫 水呈氣相之粗製曱醇的設備，在領試性設備中以不同丙酮 濃度進行複數個實驗。領試性設備係由粗製甲醇供給，蒸 發窃及最終加熱器，内徑為27.3 mm之不鏽鋼固定床反應 器及兩階段冷卻及分離組成。分離係由氣相/液相分離器 組成，其產物以冷凝物及產物氣體得到。自粗製甲醇原 料，自冷凝物及自產物氣體採出分析樣品，其中使產物氣 體額外地通過裝有曱醇之洗滌瓶，以可更精確地檢測產物 耽體中之含氧微量成份。於粗製甲醇使用氣體層析標準分 析方法，藉此可檢測醇、鱗、酿、酮及煙。 針對所有的實驗，使用以下通用實驗條件： 催化劑重量： 150 g 摧化劑類型： u錠劑％式之ύ-αι2ο3(製造商：Siid_Chemie)S 151370.doc, 〇 201121933 The liquefied in the condenser is thus separated from the low boilers such as trace gas components. In this way, a purity of >99.9% DME product is achieved. In the downstream scrubber, the gaseous overhead product of the condenser is released from the still remaining traces of DME by using the crude methanol as a detergent. The crude methanol loaded with DME is recycled to the dehydration reactor as a feed. In the second distillation stage, the sterol is obtained in the form of a overhead product which is likewise recycled as a feed to the dehydration reactor. The self-made process removes the wastewater obtained in the form of a bottom product. The numerical example is a device for explaining the limit value of the total content of the carbonyl compound to safely operate the crude sterol which is catalytically dehydrated in the gas phase, and is carried out in a pilot plant with different acetone concentrations. Multiple experiments. The pilot equipment consisted of crude methanol, steam thief and final heater, stainless steel fixed bed reactor with an internal diameter of 27.3 mm and two-stage cooling and separation. The separation system consists of a gas phase/liquid phase separator, the product of which is obtained as condensate and product gas. From the crude methanol feedstock, the analytical sample is taken from the condensate and from the product gas, wherein the product gas is additionally passed through a decyl alcohol-containing wash bottle to more accurately detect the oxygen-containing trace component in the product carcass. A gas chromatography standard analysis method is used for crude methanol, whereby alcohol, scale, brew, ketone and smoke can be detected. For all experiments, the following general experimental conditions were used: Catalyst weight: 150 g Modifier type: u Lozenges % type ύ-αι2ο3 (manufacturer: Siid_Chemie)
反應器入口溫度：300°C 反應器壓力： 16 bar(a) 空間速度： 2 kg/(kg.h)(如上所界定） 151370.doc • 14· 201121933 實驗1至4及比較實例1 以在甲醇原料中之不同丙酮濃度，另外以相同反應條件 進行實驗（實例1至4)，其中將未添加丙酮之實驗用作參照 (比較實例1)。基本結果列於下表中：Reactor inlet temperature: 300 ° C Reactor pressure: 16 bar (a) Space velocity: 2 kg / (kg.h) (as defined above) 151370.doc • 14· 201121933 Experiments 1 to 4 and Comparative Example 1 Different acetone concentrations in the methanol feed were additionally tested under the same reaction conditions (Examples 1 to 4), wherein an experiment in which no acetone was added was used as a reference (Comparative Example 1). The basic results are listed in the table below:
比較 實例1 實例1 實例2 實例3 實例4 原料中之水含量，重量％ 12 12 12 12 12 原料中之丙酮，重量ppm 0 100 2,000 10,000 100,000 曱醇轉化率 76% 78% 76-77% 76% n.d·* DME得率，以molC計 99.9% 99% 98-99% 98% n.d.* 冷凝物中未知組份(GC峰） 無 無 約70 約160 n.d.* 以曱醇吸收後，產物氣體中 未知組份(GC峰） 無 無 約90 約200 n.d.* 運行時間(最大持續50 h)後之堵塞 無 無 無 1天 <5h 固體成份 - - HMB HMB *n.d.未測定，歸因於設備之故障，無法進行各種產物流之完 全質量平衡及分析。 發現在原料.中丙酮濃度S100 wt-ppm下，未觀察到甲醇 轉化率之減弱（實例1相較比較實例1)。在2000 wt-ppm及以 上之濃度下，形成極大量之未知產物，其在冷凝物及產物 氣體（實例2)中可檢測出，但在50 h之最大操作時間後，在 領試性設備中仍未觀察到堵塞。當丙酮濃度增加至10000 wt-ppm時，未知反應產物之量明顯增加，且約1天試驗操 作後，可檢測到堵塞，以使設備必須停工（實例3)。分析造 成此堵塞之固體發現實質上皆由六甲基苯（HMB)組成。在 100000 wt-ppm之甚至更高丙酮濃度下（10重量％，根據上 述關於製造HMB之論文），無法維持常規試驗操作，此因 設備在小於5 h之試驗操作内堵塞之故。此外，沉積物係 由HMB組成。Comparative Example 1 Example 1 Example 2 Example 3 Example 4 Water content in the raw material, wt% 12 12 12 12 12 Acetone in the raw material, ppm by weight 0 100 2,000 10,000 100,000 sterol conversion 76% 78% 76-77% 76% Nd·* DME yield, 99.9% in molC 99% 98-99% 98% nd* Unknown component in condensate (GC peak) No about 70 约160 nd* After absorption by decyl alcohol, unknown in product gas Component (GC peak) No approx. 90 Approx. 200 nd* Run time (maximum 50 h). No blockage for 1 day <5h Solid component - - HMB HMB *nd not determined due to equipment failure It is impossible to perform complete mass balance and analysis of various product streams. It was found that no decrease in methanol conversion was observed in the acetone concentration S100 wt-ppm in the raw material (Example 1 compared with Comparative Example 1). At concentrations of 2000 wt-ppm and above, a very large number of unknown products are formed which are detectable in the condensate and product gas (Example 2), but after a maximum operating time of 50 h, in the pilot equipment No blockages have been observed. When the acetone concentration was increased to 10,000 wt-ppm, the amount of the unknown reaction product was significantly increased, and after about 1 day of the test operation, clogging was detected so that the equipment had to be shut down (Example 3). Analysis of the solids that caused this blockage was found to consist essentially of hexamethylbenzene (HMB). At an even higher acetone concentration of 100,000 wt-ppm (10% by weight, according to the above paper on the manufacture of HMB), the conventional test operation could not be maintained because the device was clogged in the test operation of less than 5 h. In addition, the sediment consists of HMB.
S 151370.doc -15- 201121933 實例5 在又一實驗中，檢查MEK濃度之影響，根據先前技術其 行爲應類似於丙酮且進行相似反應。在以上所述之濃度 下，進行類似於實例1至4之實驗。結果列於下表中： 原料中之水含量，wt % 12 原料中之丙酮，wt-ppm 0 原料中 MEK，wt-ppm 2000 幾基化合物之總含量(基於丙酮之質量當量） 1620 曱醇轉化率 76% DME得率，以molC計 98.2-99.6% 冷凝物中之未知組份(GC峰） 約100 曱醇吸收後，產物氣體中之未知組份(GO%) 約100 運行時間(最大持續430 h)後之堵塞 無 固體成份 - #)經由關係式計算：丙酮質量當量=戴基化合物之wt-ppmx丙酮之 莫耳質量/羰基化合物之莫耳質量 不出現設備之堵塞，但此處亦可發現藉由MEK與曱醇之 副反應可形成許多新穎未知組份。甚至有形成較在粗製曱 醇原料中以相當丙酮濃度下更多仍未知組分的趨勢（參見 實例2);此可證明MEK相較丙酮表現不對稱取代酮（各一曱 基及乙基），由此存在形成新穎產物之更多組合可能性。 實例6 在又一實驗中，在相同條件下之設備中，可確定粗製甲 醇中通常存在之其他雜質對設備操作之影響。結果列於下 表中。此進料混合物之實驗最大持久時間係430 h。相較 先前實驗，溫度亦會發生變化。 原料中之水含量，wt-% 12 原料中之丙_，wt-ppm 0 原料中MEK，wt-ppm 60 151370.doc -16- 201121933 羰基化合物之總含量(基於丙酮之質量當量） 48 原料中之乙醇，wt-ppm 1000 原料中之異丙醇，wt-ppm 280 原料中之第二丁醇，wt-ppm 280 原料中之己烧，wt-ppm 200 反應器入口溫度 280-400〇C 曱醇轉化率 70-77% DME得率，以molC計 98.7-99.7% 冷凝物中之未知組份(GC峰） 0 曱醇吸收後，產物氣體中之未知組份(GC岭） 0 運行時間(最大持續430 h)後之堵塞 無 固體成份 - 可看出如若維持戴基化合物之總含量為50 wt-ppm之所 需極限值，則在粗製甲醇中以雜質形式出現之其他含氧化 合物之存在對粗製曱醇之脫水無不利影響。此發現亦適用 於所檢測之顯著更高溫度。 實例7 為更精確地檢查丙酮與曱醇得到HMB與其他組份之非所 需反應之影響，在高壓釜中將64 g曱醇及6.4 g丙酮與173 g γ-Al2O3—起於230°C及20bar之壓力下加熱20h。持續20h 後，終止實驗並移除催化劑並分析。可清晰看出嚴重褐色 污點。分析催化劑額外揭示反應前與反應後BET表面及孔 隙體積之變化，其中在測定BET表面及孔隙體積前，在 500°C之惰性氣體下退火來自實例7之所用催化劑，以解吸 低揮發性有機組份。實驗結果列於下表中。 新鮮催化劑 退火後，自實例7之所用催化劑 BET表面，m2/g 210 187 孔隙體積，m3/g 0.480 0.378 因500°C下之除氣之重量損失 - 18.3重量％ 151370.doc -17- 201121933 可明顯看出，歸因於在粗製曱醇中極大濃度之丙嗣下發 生之非所需副反應’ bet表面及孔隙體積明顯降低。當計 算中包含18.3重量❶/❶之吸附有機分子時，則自由孔隙體積 甚至進—步降低，例如吸附物之假定密度為1·5 g/cm3較新 鮮催化劑之0.480 m3/g下降約0.12 m3/g至僅約0.26 m3/g。 由於所用之催化劑係塊狀催化劑，故諸如金屬載量或金屬 分散之其他因素與去活化無關，但反而催化活性主要係由 催化活性内表面之物理可及性所決定。因此，歸因於所觀 察到之BET表面及孔隙體積的減小，可預期運行時間及性 能較適宜操作降低，即以較低丙酮濃度之原料。 因此’極高濃度之羰基化合物之存在不僅因例如在導管 中沉積物之形成而損及製程，其將導致設備非所需之停工 並降低設備利用率’而且其等亦導致催化劑之降解並因此 產生較低甲醇轉化率及DME得率。 工業適用性 藉由本發明，因此可提供一種用於製造二甲醚之改良方 法，因使用粗製甲醇以脫水的該方法特徵在於較基於純甲 醇之方法的經濟優點。如此，節省用於處理粗製曱醇之至 少一蒸餾階段。避免大量甲醇在純甲醇塔中以低沸物之形 式蒸餾可明顯減少該方法之能量消耗。當維持專利申請範 圍中所指示之羰基化合物的極限值時，使用粗製甲醇用於 脫水係無問題的。儘管使用粗製甲醇，但所得到之〇]^£產 物具有特別低含量之干擾雜質。 151370.docS 151370.doc -15- 201121933 Example 5 In a further experiment, the effect of MEK concentration was examined and its behavior should be similar to acetone and a similar reaction according to the prior art. Experiments similar to Examples 1 to 4 were carried out at the concentrations described above. The results are listed in the table below: Water content in the feed, wt % 12 Acetone in the feed, wt-ppm 0 MEK in the feed, wt-ppm 2000 Total content of the base compound (based on the mass equivalent of acetone) 1620 Sterol conversion Rate 76% DME yield, 98.2-99.6% in molC Unknown component in condensate (GC peak) After about 100 sterol absorption, unknown component in product gas (GO%) about 100 run time (maximum duration After 430 h), there is no solid content in the blockage - #) Calculated by the relationship: acetone mass equivalent = weight-ppm of the base compound, molar mass of acetone / molar mass of the carbonyl compound, no blockage of the device, but here too It has been found that many novel unknown components can be formed by the side reaction of MEK with sterol. There is even a tendency to form more unknown components than in the crude sterol feedstock at comparable acetone concentrations (see Example 2); this demonstrates that MEK exhibits asymmetrically substituted ketones (each thiol and ethyl) compared to acetone. Thus, there are more combinations of possibilities for forming novel products. Example 6 In a further experiment, the effect of other impurities normally present in the crude methanol on the operation of the apparatus was determined in equipment under the same conditions. The results are listed in the table below. The maximum experimental duration of this feed mixture was 430 h. The temperature also changes compared to previous experiments. Water content in the raw material, wt-% 12 propylene in the raw material, wt-ppm 0 MEK in the raw material, wt-ppm 60 151370.doc -16- 201121933 Total content of carbonyl compound (based on the mass equivalent of acetone) 48 In the raw material Ethanol, wt-ppm 1000 isopropanol in the feed, wt-ppm 280 second butanol in the feed, wt-ppm 280 hexane in the feed, wt-ppm 200 reactor inlet temperature 280-400 〇C 曱Alcohol conversion 70-77% DME yield, 98.7-99.7% in molC Unknown component in condensate (GC peak) 0 Unknown component in product gas after sterol absorption (GC ridge) 0 Run time ( The maximum continuation of 430 h) is free of solids - it can be seen that if the required limit of the total content of the base compound is 50 wt-ppm, the presence of other oxygenates in the form of impurities in the crude methanol There is no adverse effect on the dehydration of crude sterols. This finding also applies to significantly higher temperatures detected. Example 7 To more accurately examine the effect of acetone and sterol on the undesired reaction of HMB with other components, 64 g of sterol and 6.4 g of acetone and 173 g of γ-Al 2 O 3 were started at 230 ° C in an autoclave. Heated for 20 h under a pressure of 20 bar. After 20 h, the experiment was terminated and the catalyst was removed and analyzed. Severe brown stains are clearly visible. The analysis catalyst additionally revealed changes in the BET surface and pore volume before and after the reaction, wherein the catalyst used in Example 7 was annealed at 500 ° C under inert gas to desorb the low volatile organic group before the BET surface and pore volume were determined. Share. The experimental results are listed in the table below. After annealing of the fresh catalyst, the BET surface of the catalyst used in Example 7, m2/g 210 187 pore volume, m3/g 0.480 0.378 due to the weight loss of degassing at 500 ° C - 18.3 wt% 151370.doc -17- 201121933 It is apparent that the undesired side reaction 'bet surface and pore volume occurring due to the extremely high concentration of propylene in the crude sterol' is significantly reduced. When the calculation contains 18.3 ❶/❶ of adsorbed organic molecules, the free pore volume is even further reduced. For example, the assumed density of the adsorbate is 1.25 g/cm3, which is about 0.12 m3 lower than the 0.480 m3/g of the fresh catalyst. /g to only about 0.26 m3/g. Since the catalyst used is a bulk catalyst, other factors such as metal loading or metal dispersion are independent of deactivation, but instead the catalytic activity is primarily determined by the physical accessibility of the catalytically active inner surface. Therefore, due to the observed decrease in the BET surface and pore volume, it is expected that the run time and performance will be reduced as appropriate, i.e., at a lower acetone concentration. Therefore, the presence of 'very high concentrations of carbonyl compounds not only damages the process due to, for example, the formation of deposits in the conduit, which will result in undesired shutdowns of the equipment and reduce equipment utilization' and also lead to degradation of the catalyst and therefore Produces lower methanol conversion and DME yield. Industrial Applicability By the present invention, it is therefore possible to provide an improved method for producing dimethyl ether, which is characterized by the economic advantage of a method based on pure methanol based on the use of crude methanol for dehydration. In this way, at least one distillation stage for processing the crude sterol is saved. Avoiding the distillation of large amounts of methanol in a pure methanol column in the form of low boilers can significantly reduce the energy consumption of the process. When the limit value of the carbonyl compound indicated in the patent application range is maintained, the use of crude methanol for dehydration is not problematic. Despite the use of crude methanol, the resulting product has a particularly low level of interfering impurities. 151370.doc