JP3628023B2 - Wax hydroisomerization - Google Patents

Description

代表的な粗ロウ供給原料は、下記表２の組成を有している。この粗ロウは、アラブライト原油から得られた40℃で65cSt（300SUS）のニュートラル油を溶剤（MEK）脱ロウして得た。

本発明の使用に適した別の粗ロウは、後記実施例３の一部として示した表６に示す特性を有する。このロウは、重質中性フルフラール抽残油の溶剤脱ロウによって調製される。先に説明したように、水素化異性化に用いる粗ロウを調製するために、水素化分解を採用してもよい。
水素化分解プロセス（必須ではない工程）
予備処理工程として水素化分解を採用するなら、比較的高いパラフィン性の水素化分解生成物を製造するように、供給原料中の低品質芳香族成分の飽和および開環を促進するために無定形二官能性触媒を使用するのが好ましい。水素化分解は、芳香族の飽和に有利な高圧で実施するが、その沸点範囲の転換は、比較的低い水準に保持し、これにより供給原料の飽和成分の分解を最小にすると共に芳香族成分の飽和および開環から得られた生成物の分解を最小にする。このような方法の目的と一致させるため、水素化分解階段における水素圧は、少なくとも約5500kPa_a（800psig）であり、通常6900（1000psig）〜20700kPa_a（3000psig）の範囲にある。一般に、少なくとも10500kPa_a（1500psig）の水素分圧が、高い水準の芳香族飽和を達成するためには、最もよい。少なくとも約178n.l.l.^-1（1000SCF/Bbl）、好ましくは900（2000SCF/Bbl）〜1800n.l.l.^-1（8000SCF/Bbl）の範囲の水素循環速度が適している。
水素化分解プロセスでは、本発明の特徴である所望の高い単流収率を維持するために、潤滑油沸点範囲未満で沸騰する生成物、代表的には345℃−（650゜F−）生成物への供給原料の転化は、供給原料の50重量％以下、通常は30重量％以下に制限される。実際の転化率は、供給原料の品質に依存すると共に、粗ロウ供給原料は、より低品質の多環式成分の除去が必要なペトロラタム（非晶質ロウ）に比べて、より低い転化率で足りる。中性原料の脱ロウから得られた粗ロウ原料の場合、345℃−（650゜F−）生成物への転化率は、実際には10〜20重量％を越えず、ほとんどの粗ロウについて代表的には５〜15重量％である。ペトロラタム原料は、代表的には低品質の成分をより多く含んでいるため、その転化率はより高くしてもよい。ペトロラタム供給原料について、水素化分解の転化率は、高粘度指数の生成物を製造するには、代表的には15〜25重量％である。転化率は、水素化分解段階の温度制御によって所望の値に維持することができる。そのような温度は、315〜430℃（600〜800゜F）、より一般的には約345〜400℃（650〜750゜F）である。空間速度の変化も苛酷度の制御に利用できるが、システムに対する機械的制約の面から、実際には一般的ではない。通常、空間速度は0.25〜2LHSV,hr^-1であり、一般に0.5〜1.5LHSVである。
水素化分解操作の特徴は、二官能性触媒を用いることである。一般的に言うと、このような触媒は、所望の芳香族の飽和反応を促進する金属成分を含んでおり、通常、鉄族（VIII族）の金属とVI B族の金属とを組み合わせた卑金属の組み合わせが用いられる。すなわち、ニッケルまたはコバルトのような卑金属をモリブデンまたはタングステンと組み合わせて用いる。好ましい組み合わせは、ニッケル／タングステンである。これは、この組み合わせが所望の芳香族水素化分解反応を促進するのに非常に効果的だからである。白金またはパラジウムのような貴金属も、硫黄が存在しない場合には良好な水素化活性を有しているので用いることができるが、通常はそれ程好ましくない。触媒上に存在する金属の量は、この種の潤滑油水素化分解触媒について通常の量であり、一般に、触媒全重量に対して、VIII族金属１〜10重量％およびVI族金属10〜30重量％である。ニッケルまたはコバルトのような卑金属に代えて、白金またはパラジウムのような貴金属成分を用いる場合、これら貴金属はより高い水素化活性を示すため、比較的少ない量でよく、代表的には、約0.5〜５重量％で十分である。金属は、あらゆる適当な方法で組み込むことができ、例えば、多孔質担体を所望寸法の粒子に形成した後にこの担体に含浸させたり、焼成の前に担体物質のゲルに添加することなどによって組み込むことができる。ゲルへの添加は、比較的多量の金属成分、例えばVIII族金属10重量％以上およびVI族金属約20重量％以上を添加する場合に、好ましい方法である。これらの方法は通常の方法であり、潤滑油水素化分解触媒の製造に用いられている。
触媒の金属成分は、一般に、多孔質無定形の金属酸化物担体に担持され、この目的にはアルミナが好ましいが、シリカ−アルミナも用いることができる。他の金属酸化物成分も、担体中に存在させてもよいが、その存在はやや好ましくない。潤滑油水素化分解触媒の条件に一致させるため、担体は、高沸点供給原料中の比較的嵩高い成分が触媒の内部孔構造に入って、そこで所望の水素化分解反応が起こるのに充分な孔径および分布を有する必要がある。この点で、触媒は通常約50Åの最小孔径を有する。すなわち、約５％以上の孔が50Å未満の孔径を有すると共に、孔の大多数は50〜400Åの孔径を有する（５％を越えない孔が400Åを越える孔径を有する）。好ましくは、約30％以下の孔が200〜400Åの孔径を有する。水素化分解に適した触媒は、その孔の少なくとも60％が50〜200Åの範囲にある。水素化分解への使用に適したいくつかの代表的な潤滑油水素化分解（LHDC）触媒の孔径分布および他の特性を下記表３に示す。

所望の転化率を得る為に必要なら、触媒調製時に触媒にフッ素を導入するかまたは供給原料に添加したフッ素化合物の存在下に水素化分解を行うことによって、触媒の性能をフッ素によって向上させることができる。フッ素含有化合物は、調製時に適当なフッ素化合物、例えばフッ化アンモニウム（NH₄F）または二フッ化アンモニウム（NH₄F・HF）を含浸することによって触媒に組み込むことができるが、これらのアンモニウムうち、後者が好ましい。フッ素含有触媒中に含まれるフッ素の量は、触媒の全重量に対して、通常約１〜10重量％、好ましくは約２〜６重量％である。フッ素は、触媒調製時にフッ素化合物を金属酸化物担体のゲルに添加するかまたはゲルを乾燥または焼成して触媒粒子を形成した後に含浸することによって、組み込むことができる。先に記載したように、触媒が比較的多量のフッ素と多量の金属を含む場合、ゲルの乾燥および焼成の前に金属酸化物ゲルに金属およびフッ素化合物を組み込んで最終触媒粒子を形成することが好ましい。
またその場での（系内での）フッ素化、例えば操作のこの段階で触媒上を通過する流れにフッ素化合物を添加することによって、触媒活性を所望の水準に保つことができる。フッ素化合物は、供給原料に連続的または断続的に添加することができ、これとは別の態様として、供給原料の不存在下に、例えば水素気流中でフッ素化合物を触媒上に流して初期活性化工程を実施し、これにより実際に水素化分解が開始される前に触媒中のフッ素含量を増すこともできる。触媒のその場でのこのようなフッ素化は、好ましくは、操作の前にフッ素含量が約１〜10％となるように行い、その後、フッ素を、所望の活性維持に十分な維持水準に減少させることができる。その場でのフッ素化に適した化合物は、オルトフルオロトルエンおよびジフルオロエタンである。
触媒上に存在する金属は、好ましくは硫化物の形で用いられ、その為に、水素化分解の開始前に触媒の予備硫化処理を行わなければならない。硫化処理は、確立された技術であって、代表的には、通常水素の存在下に、触媒を硫黄含有ガスに接触させて行う。このためには、水素と、硫化水素、二硫化炭素またはメルカプタン（例えばブチルメルカプタン）との混合物が一般的である。予備硫化処理は、触媒を水素および硫黄含有炭化水素油、例えばサワーケロシンまたは軽油と接触させることによっても行える。
水素化異性化
もとのロウ供給原料中に存在するパラフィン系成分は、高い粘度指数を有しているが、その流動点は比較的高い。従って、本発明の方法の目的は、潤滑油成分としてのより分岐した種の転化を最小にしながら、ロウ質種の選択的転化を行うことにある。ロウの転化は、異性化が優先的に生じ、これにより、より低い流動点および曇点を有するより分岐した種を生成する。ある程度の分解が異性化に伴って起こり、この分解の程度は、ロウの転化率によって変化する。
水素化異性化触媒
本発明の水素化異性化に用いる触媒は、ロウ質の直鎖またはほぼ直鎖のパラフィン類をロウ特性が低いイソパラフィン系生成物に異性化するような高選択性の触媒である。この種の触媒は、特性として二官能性であって、比較的酸性度が低い大孔径の多孔質担体に担持された金属成分を含んでいる。酸性度は、操作のこの段階の間に潤滑油沸点範囲外の沸点を有する生成物への転化を減少させるために、低い水準に保たれる。一般的に言うと、触媒は、金属の添加前に30未満のアルファ値を有すべきであり、好ましいアルファ値は20未満である（実施例１参照）。
アルファ値は、標準触媒と比べた触媒の接触分解活性のおおよその指標である。アルファ試験では、アルファ値を１とする標準触媒（速度定数＝0.016sec^-1）に対する、試験触媒の相対的速度定数（単位時間および触媒の単位体積当たりのｎ−ヘキサンの転化速度）が得られる。アルファ試験は、米国特許第3,354,078号、並びにジャーナル・オブ・キャタリシス（J.Catalysis）第４巻527頁（1965年）；同第６巻278頁（1966年）；および同第61巻395頁（1980年）に記載されている。これらを、試験方法の記述について参照する。本明細書に示したアルファ値を決定するのに採用した試験の実験条件は、538℃の定温およびジャーナル・オブ・キャタリシス第61巻395頁（1980年）に記載されている可変流量を含む。
水素化異性化触媒は、大孔のモレキュラーシーブ、一般にゼオライトまたはシリカ／アルミノホスフェートを含む。大孔モレキュラーシーブは、多孔質バイダーに担持されている。大孔ゼオライトは、通常、酸素12員環からなる少なくとも１つの孔路を有している。大孔ゼオライトは、通常、７Åよりも大きい主寸法を有する少なくとも１つの孔路を有している。ゼオライトベータ、Ｙおよびモルデン沸石（モルデナイト）は、大孔ゼオライトの例である。
本発明の触媒は、異性化：分解の相対的比率を最大化するため、0.1ミクロン未満の結晶直径を有する。小さい直径の結晶によって、異性化した種は結晶構造から容易に拡散することができ、これによりその分解に必要なポテンシャルが減少する。
好ましい水素化異性化触媒は、ゼオライトベータを使用する。これは、このゼオライトベータが、米国特許第4,419,220号に開示されているように、芳香族の存在下でのパラフィン異性化に対して顕著な活性を有することが示されているからである。ゼオライトベータの低酸性度形態は、高シリカ含量形態のゼオライト、例えばシリカ：アルミナの比率が約500:1以上のゼオライトの合成によって得られ、より簡単には、低シリカ／アルミナ比のゼオライトを所望の酸性度水準にまでスチーム処理することによって得ることができる。また、ゼオライトベータは、米国特許第5,200,168号に開示されているように、酸、例えばカルボン酸によって抽出することによっても得ることができる。米国特許第5,164,169号は、合成用混合物中に四級アルケノールアミンのようなキレート化剤を用いる、高シリカゼオライトベータの製造を開示している。米国特許第3,308,069号は、0.01〜0.05ミクロンの結晶径を有するゼオライトベータの合成を開示する。この範囲の結晶径の触媒は本発明に使用される。本発明の結晶径は0.1ミクロンを越えなく、0.01〜0.05ミクロンの結晶径が好適である。
最も好ましいゼオライトは、激しくスチーム処理され、その骨格のシリカ／アルミナ比は、200:1以上、好ましくは400:1以上である。
スチーム処理条件は、最終の触媒において所望のアルファ値が得られるように調節すべきであり、代表的には温度約427℃〜595℃（800〜約1100゜F）で100％のスチーム雰囲気を用いる。通常、スチーム処理は、酸性度を所望通り低下させるために、538℃（1000゜F）以上の温度において約12〜120時間、代表的には約96時間行われる。
低酸性度ゼオライトベータ触媒の別の製造法は、ゼオライトの骨格アルミニウムの一部を他の３価原子、例えばホウ素により置換することであって、これによりゼオライトのより低い固有の水準の酸活性度が得られる。この種の好ましいゼオライトは、骨格にホウ素を含むものである。通常、ホウ素は、他の金属の添加前にゼオライト骨格に添加される。この種のゼオライトでは、骨格は、四面体配位しかつ酸素架橋によって相互に結合された珪素から主として構成される。少量の元素（アルミノシリケートゼオライトベータの場合はアルミニウム）も配位し、骨格の一部を形成する。また、ゼオライトは、ゼオライトの特徴的な構造を構成する骨格の一部を形成しないような物質を、構造の孔中に含んでいてよい。本明細書において用いられる「骨格」ホウ素なる語は、ゼオライトのイオン交換能に寄与するゼオライトの骨格中の物質を、孔中に存在する物質であってゼオライトの全体のイオン交換能に影響を与えない物質から区別するために使用する。ゼオライトベータは、316℃〜399℃の温度において0.60〜2.0の拘束指数を有するが、１未満の拘束指数が好ましい。
骨格ホウ素を含む高シリカ含量のゼオライトの製法は、例えば米国特許第4,269,813号に開示され、知られている。骨格ホウ素含有ゼオライトベータの製法は、米国特許第4,672,049号に開示される。そこに開示されているように、ゼオライト中に含まれるホウ素の量は、例えばシリカおよびアルミナ組成に対しホウ酸の量を変化させて、ゼオライト形成溶液中に種々の量のホウ素イオンを組み込むことによって、変化させることができる。ゼオライトの製法の記載に関するこれらの開示を参照する。
低酸性度ゼオライトベータ触媒は、少なくとも0.1重量％、好適には少なくとも0.5重量％の骨格ホウ素を含むべきである。他の金属の添加前に、骨格にホウ素を添加してもよい。一般に、ホウ素の最大量は、ゼオライトの約５重量％、殆どの場合には２重量％以下とすることができる。骨格は通常いくらかのアルミナを含むことができる。シリカ：アルミナの比率は、合成したゼオライト状態において通常少なくとも30:1とすることができる。好適なホウ素置換ゼオライトベータ触媒は、少なくとも１重量％のホウ素をB₂O₃として含むホウ素含有ゼオライトをスチーム処理して、約20以下、好適には10以下の最終アルファ値が得られるように、製造される。
特性
酸性度は、水素化異性化触媒に対し、供給原料と共にアンモニア（NH₃）、有機窒素化合物などの窒素化合物を導入することによって減少させることができる。ただし、供給原料中の総窒素含量は、100ppmを越えるべきでなく、好適には少なくとも20ppm未満である。触媒は、またこの触媒の強酸部位の数を減少させて分解反応に対する異性化反応の選択性を改善するような、金属を含んでもよい。このために好適な金属は、カルシウムやマグネシウムのようなII A族金属の部類に属するものである。
ゼオライトは、最終の触媒を形成するためマトリックス材料を含む複合体とすることができ、この目的には、従来からの非常に酸性度が低いマトリックス材料、例えばアルミナ、シリカ−アルミナ、シリカなどが適しているが、アルファベーマイト（アルファルミナ一水化物）のようなアルミナも、マトリックス化触媒の酸性度に実質的に影響を与えない限り、使用することができる。ゼオライトは、通常80:20〜20:80、代表的には80:20〜50:50のゼオライト：マトリックスの重量比のマトリックス量で複合体化される。常法、例えば材料を混練し、次いで所望の最終触媒粒子を押出成形して、複合体化を行うことができる。バインダーとしてシリカを含有するゼオライトの好適な押出成形法は、米国特許第4,582,815号に開示される。所望の低酸性度を達成するために触媒をスチーム処理すべき場合、従来法のように、バインダーを用いて触媒を配合した後にスチーム処理を行う。スチーム処理用の触媒の好適なバインダーはアルミナである。
また水素化異性化触媒は、不飽和遷移種を介して進行し、水素化−脱水素化成分の介在を必要とする所望の水素化異性化反応を促進するような金属成分を含んでもよい。この理由のため、触媒の異性化活性を最大にするには、強力な水素化機能を示す金属が好適であり、白金や他の貴金属、例えばレニウム、金、パラジウムなどが好適である。貴金属水素化成分の量は、代表的には触媒全量の0.1〜５重量％、通常は0.1〜２重量％である。白金テトラアミンなどの錯体白金カチオンとのイオン交換や、可溶性の白金化合物、例えばテトラアミン塩化白金などの白金テトラアミンの塩の含浸を含め、常法によって白金を触媒に組み込むことができる。触媒は、通常の条件下に最終の焼成処理に付して、貴金属をその還元形態にさせると共に触媒に必要な機械的強度が得られる。触媒は、その使用前に水素化分解予備処理触媒用の前記予備硫化処理に付してもよい。
水素化異性化条件
水素化異性化工程（異性化工程とも呼ぶ）の条件は、ロウ質供給原料中のロウ質、直鎖およびほぼ直鎖のパラフィン系成分の、ロウ質は少ないが高い粘度指数であって比較的低流動点のイソパラフィン系物質への異性化の目的を達成するように、調節される。この目的は、非潤滑油沸点範囲の生成物（345℃−（650゜F−）の物質）への転化を最小にしながら達成される。水素化異性化に使用される触媒は低い酸性度を有するため、低沸点生成物への転化は、通常比較的低い水準であり、また好適な苛酷度の選択によって、プロセスの操作を分解よりも異性化にとって最適化することができる。約１の通常の空間速度において、20未満のアルファ値の白金／ゼオライトベータ触媒を用い、水素化異性化の温度を代表的には約300〜415℃（約570〜約780゜F）の範囲とすると共に、345℃−（650゜F−）生成物への転化率を、代表的にはロウ質供給原料の約５〜30重量％、より一般的には10〜25重量％とする。
水素化異性化は、少なくとも5516kPaa（800psig）、通常は5167〜20786kPaa（800〜3000psig）、最も通常には5516〜17340kPaa（800〜2500psig）の水素分圧（反応器入口）で操作される。水素循環速度は、通常は約90〜900n.l.l.^-1（500〜5000SCF/Bbl）の範囲である。もとの供給原料中に存在する芳香族系成分は、触媒上の貴金属水素化成分の存在下に多少とも飽和反応が生じるため、所望の異性化反応が水素バランスの状態の場合でさえ水素は水素化異性化において消費される。この理由から、水素循環速度は、供給原料の芳香族含量および水素化異性化に使用される温度にしたがい調節することが必要となりうる。なぜなら、より高温では、より高い水準での分解および、その結果としてのより高い水準でのオレフィンの生成を伴うからであり、これらのうちのいくつかは、潤滑油沸点範囲のものであり、このため生成物の安定性を、飽和によって確実にすることが必要である。少なくとも180n.l.l.^-1（1000SCF/Bbl）の水素循環速度によって、所期の水素消費を補償するためならびに触媒の老化速度の低下を補償するために十分な水素が通常得られる。
床間の急冷は、プロセスの温度の維持に望ましい。急冷剤として冷却水素が一般に使用されるが、液体急冷剤、通常は再循環生成物も使用することができる。
脱ロウ
所望の流動点を達成するため、供給原料のロウ含量に応じて最終の脱ロウ工程が必要となりうる。必要な脱ロウ度が比較的小さいことが本発明の顕著な特徴である。代表的には最終の脱ロウ工程時における損失は、脱ロウ装置中の供給原料の15〜20重量％またはそれ以下とすることができる。接触脱ロウまたは溶剤脱ロウのいずれかをこの時点で使用することができ、溶剤脱ロウ装置を用いる場合、除去したロウを水素化異性化に再循環して、この異性化工程に再度通過させてもよい。脱ロウ装置による生成物脱ロウの必要性は比較的小さく、この点で、本発明は、著しい脱ロウ化度を必要とするような単一の無定形触媒を用いる方法に比し、顕著な改善を提供する。ゼオライト触媒の異性化選択性が高いため、前記無定形触媒法の50％に比し、代表的には約80％もの高い単流ロウ転化率を達成することができ、これにより装置の処理量が著しく向上する。
形状選択性脱ロウ触媒は、溶剤脱ロウ法よりも、むしろこれに代えて使用することができる。この触媒は、ｎ−パラフィンと共にわずかに分岐した鎖のロウ質パラフィンを除去する一方、より分岐した鎖のイソパラフィンをプロセス流中に残す。形状選択性接触脱ロウ方法では、異性化触媒ゼオライトベータよりもｎ−パラフィンおよびわずかに分岐した鎖のパラフィンをより高度に選択するような触媒を用いる。選択的接触脱ロウ法は、米国特許第4,919,788号記載のように実施する（この段階の記載について、この米国特許の開示を参照する）。本発明の方法の接触脱ロウ工程は、好適にはアルミノシリケートのような拘束された中間孔寸法の結晶性物質をベースとする、拘束された形状選択性脱ロウ触媒を用いて実施する。拘束された中間孔寸法の結晶性物質は、少なくとも１つの酸素10員環の孔路と共に、８員環を有する交差孔路を有する。ZSM−23は、この目的に好適なゼオライトであるが、他の高度に形状選択性のゼオライト、例えばZSM−22または合成フェリエライトZSM−35を、とくに軽質の原料について使用できる。シリカアルミノホスフェート、例えばSAPO−11およびSAPO−41も選択性脱ロウ触媒として使用することができる。
脱ロウ触媒としての使用に適した触媒は、比較的拘束された中間孔寸法のゼオライトである。このような好適なゼオライトは、米国特許第4,016,218号記載の方法によって測定されているように、１〜12の拘束指数を有する。またこれら好適なゼオライトは、それらの比較的拘束された拡散特性に関連する特異的な収着特性を特徴とする。この収着特性は、ゼオライト、例えばゼオライトZSM−22、ZSM−23、ZSM−35およびフェリエライトについて米国特許第4,810,357号に示された特性である。これらのゼオライトは、以下のような特異的な組合せの収着特性が得られるような孔開口部を有する：
（１）P/P_o＝0.1並びに温度50℃（ｎ−ヘキサン）および温度80℃（ｏ−キシレン）で測定した、約３を越えるｎ−ヘキサン:o−キシレンの収着比（容量％基準）、および
（２）温度538℃（1000゜F）で測定した約２を越えるk_3MP/k_DMBの速度定数比でもって、ｎ−ヘキサン/3−メチルペンタン/2,3−ジメチルブタン混合物（重量比1/1/1）から、1000゜Fおよび１気圧において２つの分岐を持つ2,3−ジメチルブタン（DMB）よりも３−メチルペンタン（3MP）を選択的に分解する能力。
前記式:P/P₀は、例えば文献〔“The Dynamical Character of Adsorption"（J.H.deBoer）２版、Oxford University Press（1968）〕に記載のようなその通常の意味と一致しており、また収着温度における収着質の分圧：収着質の蒸気圧の比率として定義される相対的圧力である。速度定数比、k_3MP/k_DMBは、一次速度論から、常法に従い、以下の式によって決定される：
ｋ＝（1/T_c）ln（1/1−ε）
式中、ｋは、各成分の速度定数、T_cは接触時間、εは各成分の転化率である。
これらの収着条件に適合するゼオライトには、天然のゼオライトフェリエライト並びに合成ゼオライトZSM−22、ZSM−23およびZSM−35が包含される。これらのゼオライトは、本発明の方法に使用する場合、少なくとも部分的に酸形または水素形である。
ゼオライトZSM−22の調製および特性は、米国特許第4,810,357号（Chester）に記載されており、この開示をもって本明細書の記載とする。
合成ゼオライトZSM−23は米国特許第4,076,842号および第4,104,151号に記載され、このゼオライト、その調製および特性についての開示をもって本明細書の記載とする。
ZSM−35と呼ばれる中間孔寸法の合成結晶性物質（「ゼオライトZSM−35」または単に「ZSM−35」）は、米国特許第4,016,245号に記載されており、このゼオライトおよびその調製についての開示をもって本明細書の記載とする。SAPO−11の合成は、米国特許第4,943,424号および第4,440,871号に記載される。SAPO−41の合成は、米国特許第4,440,871号に記載される。
フェリエライトは、文献記載の天然の鉱物であり（例えばD.W.Breck,ZEOLITE MOLECULAR SIEVES,John Wiley and Sons（1974）125〜127、146、219および625頁参照）、このゼオライトについての開示をもって本明細書の記載とする。
形状選択性接触脱ロウに使用する脱ロウ触媒には金属水素化−脱水素化成分が包含される。この成分は、選択性分解反応の促進に厳密には必要でないかもしれないが、この成分の存在は、２触媒脱ロウ系の相乗作用に寄与する、ある種の異性化反応の促進に望ましいことが判明した。金属成分の存在は、生成物の改善、とくに粘度指数の改善および安定性並びに触媒老化の遅延寄与につながる。形状選択性接触脱ロウは、通常水素雰囲気下に加圧して実施する。金属は、好適には白金またはパラジウムである。金属成分の量は、代表的には0.1〜10重量％とできる。マトリックス材料およびバインダーは必要に応じて使用することができる。
高度に拘束された高形状選択性の触媒を用いる形状選択性脱ロウは、第１異性化段階について前記した方法のような、他の接触脱ロウ方法と同じ常法で実施することができる。形状選択性接触脱ロウ工程についてのより詳細な説明は、米国特許第4,919,788号を参照のこと。
脱ロウ工程における低沸点種への転化度は、この時点で所望の脱ロウ化度、即ち目標とする流動点と異性化工程からの流出物の流動点との差にしたがい変化させることができる。また転化度は、使用する形状選択性触媒の選択率に依存しうる。より低い生成物流動点において、比較的小さい選択性の脱ロウ触媒を用いれば、より高い転化率および対応するより高い水素消費量を被る。
油の流動点を選択的脱ロウによって所望の値に低下させたのちに、脱ロウした油を水素化処理などの処理に付して、着色体を除去すると共に所望の特性の潤滑油生成物を製造することができる。また分別結晶化を用いて、軽質油分を除去して揮発度の規格に適合させることができる。
生成物
本発明の方法による生成物は、優れた収率で得られる、高粘度指数および低流動点の物質である。優れた粘度特性を有することに加え、本発明の生成物は、酸化的に、熱的におよび紫外線に対し非常に安定性が高い。プロセスに好適なロウ供給原料を用いれば、130〜150範囲の粘度指数値が代表的に得られ、また少なくとも140の値を、もとのロウ供給原料に基づき少なくとも50重量％、通常少なくとも60重量％の生成物収率でもって容易に達成できる。
実施例
実施例１
65重量％のゼオライトベータと35重量％のシリカ（SiO₂）の混合物を、まず押出成形して、低酸性度ゼオライトベータを含む触媒を製造した。この製造に用いたゼオライトベータは、SiO₂/Al₂O₃の比が600で、平均結晶径が１〜３ミクロン（走査電子顕微鏡（SEM）で測定）である（この合成の詳細は、米国特許第5,232,579号、第5,164,169号および第5,164,170号を参照）。ゼオライトベータとシリカの混合物を苛性アルカリ水溶液と混合してペーストを形成し、次いで触媒製造の標準法に従い押出成形した。押出成形物を、250゜Fで８時間乾燥し、次いで5v/vの1N NH₄NO₃溶液に接触させてそのナトリウム含量を減少させた。次にナトリウム減少押出成形物を、窒素雰囲気下に482℃（900゜F）に加熱し、この温度で３時間保持し、その後538℃（1000゜F）の空気に６時間露出してゼオライトベータの製造に用いた有機化合物を分解させた。次にこの触媒を、100％スチームに対し101kPa_a（0psig）で充分な時間（24時間）露出して、そのアルファ活性値を15未満に減少させた。
このスチーム処理した失活ゼオライトベータを含む材料を、次いでpH7〜８に維持したテトラアミン塩化白金二水化物の水溶液によって交換した。白金交換した触媒を、水洗して塩化物を除去し、次いで349℃（660゜F）に大気中で加熱し、この温度で３時間保持した。最終の触媒は、白金0.6重量％を含み、以下の表４に示す特性を有する。

実施例２
65重量％のゼオライトベータと35重量％のシリカ（SiO₂）の混合物を、まず押出成形して、ゼオライトベータを含む触媒を製造した。この製造に用いたゼオライトベータは、SiO₂/Al₂O₃の比が50で、平均結晶径が0.05ミクロン未満（走査電子顕微鏡（SEM）で測定）であって、MIDWグレイドのゼオライトベータについての標準法にしたがい合成した。ゼオライトベータとシリカの混合物を、苛性アルカリ水溶液と混合してペーストを形成し、次いで触媒分野の標準法に従い押出成形した。押出成形物を121℃（250゜F）で８時間乾燥した。次いでナトリウム含有押出成形物を、窒素雰囲気下に482℃（900゜F）に加熱し、この温度で３時間保持し、その後538℃（1000゜F）の空気に６時間露出してゼオライトベータの製造に用いた有機化合物を分解させた。次にこの触媒を、2Mシュウ酸水溶液に71℃（160゜F）で合計６時間接触した。次いでシュウ酸処理ゼオライトベータ触媒を538℃（1000゜F）に、２時間加熱した。この物質は、10未満のアルファ値および525ppmwのナトリウム含量を有する。
次いで、シュウ酸処理したゼオライトベータ触媒を、pH5〜６に維持したテトラアミン塩化白金二水化物の水溶液によって交換した。白金交換した触媒を、水洗して塩化物を除去し、次いで349℃（660゜F）に大気中で加熱し、この温度で３時間保持した。最終の触媒は、白金0.5重量％を含み、前記表４に示す特性を有する。
実施例３
溶剤脱ロウによる97cSt（450SUS）の重質中性フルフラール抽残油から得た粗ロウを、穏やかな苛酷度で水素化分解して、その硫黄含量および窒素含量を減少させた。穏やかな水素化分解工程の条件は、2LHSV、404℃（760゜F）および水素分圧13891kPa_a（2000psig）である。粗ロウの特性およびストリッピングした水素化分解生成物を表５に示す。
穏やかな水素化分解工程によって、粗ロウ供給原料の16％が沸点343℃（650゜F）未満の生成物に転化し、また供給原料中のロウの17％が転化した。ロウの転化率および潤滑油の収率は、以下の式によって算出する。脱ロウ油の収率は、統一のため０゜Fの流動点に補正した。
ロウ転化率＝100×〔（供給原料のロウ含量
−反応生成物のロウ含量）／供給原料のロウ含量〕
ロウ収率＝（ロウ供給原料に対する蒸留釜残油の収率）
×（溶剤脱ロウ装置供給原料にに対する
溶剤脱ロウからの油非含有ロウの収率）
潤滑油収率＝100−ロウ収率
−模擬蒸留によって測定した650゜F＋の転化率

実施例４
実施例３の穏やかな水素化分解粗ロウを、実施例１および２の白金／ゼオライトベータ触媒を用い、別々の実験によって反応させた。反応条件は、実施例１の触媒については13891kPa_a（2000psig）および1LHSVを用い、実施例２については1.25LHSVを用いた。触媒温度を変化させて反応の苛酷度を変化させた。液体供給原料の導入前に、混合物（H₂S/H₂＝2:98（容量％））によって、最大温度371℃（700゜F）で両方の触媒を予備硫化処理した。
これらの実験からの反応器流出物を模擬蒸留によって分析して、343℃−（650゜F−）生成物の転化率を決定し、次いで公称343℃（650゜F）のカットポイントで蒸留した。ロウ収率、潤滑油収率およびロウ転化率を、実施例３の式に基づき算出して、表６に示す。図は、２つの触媒のロウ転化率に対する潤滑油収率の相対的依存性を示す。
小結晶触媒のロウ異性化選択性（実施例２）は、大結晶触媒（実施例１）に比し、著しく高い。潤滑油の収率は、小結晶白金／ゼオライトベータ（Pt/B）触媒については64％でピークを示す一方、大結晶触媒についてはわずか52％に達するにすぎない。異性化とその後の形状選択性分解の連続反応系を調和させると、両方の触媒は、低いロウ転化率（40％未満）において同様な収率が得られる。しかしながら、反応の苛酷度が増加するにつれて、異性化速度に対する大結晶触媒の分解速度が増加し、これにより50％のロウ転化率において、異性化による潤滑油の生成速度は、分解による潤滑油の損失速度と整合する。この時点を越えてロウ転化率を増加させると、潤滑油の収率が減少する。これとは対照的に、異性化：分解の比率は、小結晶触媒については高いロウ転化率に至るまで高く維持される。２つの反応速度は、ロウ転化率が80％に達するまでに等しくはならなかった。
本発明の実際の有用性は、小結晶の触媒による明白な高い収率の他に、高いロウ転化率における選択的作用に対するこの触媒の能力である。この能力によって、ロウの再循環量が減少すると共に、所定量の高粘度指数ベースストックの生産に必要な反応器の寸法が減少する。
またゼオライトの酸性度は、異性化選択性の決定に重要な役割を果たすことができる。大結晶の白金／ゼオライトベータ触媒は、小結晶触媒に比し高いアルファ値を有し（13対８）、これら触媒間で観察された選択性の差は、主として酸性度の関数とはならないようである。アルファ値の差は実質的に大きくはない。

TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for producing a high viscosity index lubricating oil by isomerizing petroleum wax using a large pore zeolite having a small crystal diameter. The wax may be hydrocracked before isomerization. The isomerization product can be further dewaxed with either a solvent or a catalyst to achieve the target pour point.
Background of the Invention
Traditionally, mineral-based lubricants have been produced by a separate continuous process carried out in a refinery, i.e. fractionation of paraffinic crude oil under atmospheric pressure followed by fractionation under reduced pressure. A fraction (neutral oil) and a residual fraction are obtained, which can also be used as a lubricant basestock after deasphalting and severe solvent treatment. This refined residual fraction is usually called bright stock. Neutral oils have traditionally been solvent extracted to remove low viscosity index (V.I.) components and then dewaxed by a solvent or catalytic dewaxing process to achieve the desired pour point. The dewaxed lubricant stock may be hydrofinished to improve stability and remove colored components. The viscosity index reflects the rate at which the viscosity of the lubricating oil decreases with increasing temperature. Products from solvent dewaxing are dewaxed lubricating oil and crude wax (slack wax). Crude wax typically contains 60-90% wax, with the balance being entrained oil. In some cases, the crude wax is diluted with a dewaxing solvent and then filtered at a temperature higher than the temperature of the filtration process used to produce the crude wax, thereby attaching the crude wax to the dewaxing process, thereby removing the entrained oil. It is desirable to remove the crude wax and purify it. Refined wax is called deoiled wax and contains over 95% wax. The second filtration by-product typically contains 50% wax and is referred to as wax wax oil.
Catalytic dewaxing of the lubricant stock can be done by converting waxy molecules to light products by decomposition, or by isomerizing the waxy molecules to form molecular species that remain in the dewaxed lubricant. The dewaxing catalyst mainly decomposes cyclic and hyperbranched molecular species generally contained in the dewaxed lubricating oil while allowing easy access to the catalytic active sites of the substantially linear molecules that normally constitute the wax. By having a pore structure that inhibits, a high yield is retained. A catalyst that significantly reduces the accessibility of molecular species based on the size of the molecule is called shape selectivity. Increasing the shape selectivity of the dewaxing catalyst often increases the yield of dewaxed oil.
The shape selectivity of the dewaxing catalyst is actually limited by its ability to convert waxy molecules with slightly branched structures. This type of molecular species is more commonly associated with heavier lubricant stocks such as bright stocks. If the shape selectivity of the dewaxing catalyst is higher, it would not be possible to convert heavy branched wax species that would turbidize the appearance of the lubricating oil at room temperature and give a higher cloud point than the pour point.
Traditional lube oil refining technology relies on the proper selection and use of crude stock, which usually exhibits paraffinic properties, so that a sufficient amount of lube oil fraction of the desired quality is produced. The However, the range of acceptable raw materials can be expanded by a lubricating oil hydrocracking process that can use marginally poor quality crude stocks that usually have higher aromatic content than the best paraffinic crude stock. it can. Lubricating oil hydrocracking processes are well established in the petroleum refining industry and generally include the first hydrocracking step, which involves the partial saturation and opening of aromatic components present in the feed at high pressures and temperatures. It is carried out in the presence of a bifunctional catalyst that produces a ring. The hydrocracked product is then subjected to dewaxing to reach the target pour point. This is because hydrocracking products usually contain relatively high pour point molecular species. In many cases, the liquid product from the dewaxing process is subjected to a low temperature high pressure hydrotreatment to reduce the aromatic content of the lubricating oil to a desired level.
Current trends in automotive engine design are toward higher operating temperatures as engine efficiency increases. Such higher operating temperatures therefore require higher quality lubricants. One requirement is for a higher viscosity index to reduce the effect of higher operating temperatures on engine lubricant viscosity. High viscosity indexes have heretofore been achieved by using viscosity index improvers such as polyacrylates and polystyrene. Viscosity index improvers are susceptible to degradation due to the high temperatures and high shear rates that occur in the engine. Due to the more severe conditions that occur in high performance engines, oils that use large amounts of viscosity index improvers degrade faster. Therefore, there continues to be a need for automotive lubricants that are based on liquids having a high viscosity index and that are resistant to the high temperature and high shear rate conditions that occur in modern engines.
Synthetic lubricating oils produced by polymerizing olefins in the presence of certain catalysts are known to have excellent viscosity indices, but are relatively expensive to produce. Accordingly, there is a need to produce high viscosity index lubricants from mineral oil stocks that can be produced by techniques comparable to those currently employed in petroleum refining.
U.S. Pat. No. 4,975,177 discloses a two-stage dewaxing process for producing a high viscosity index lubricant stock from a waxy feed. In the first stage of the process, the waxy feed is catalytically dewaxed by isomerization using a noble metal-containing zeolite beta. In that example, 6996kPa_aA mild acidity catalyst with a pressure below (1000 psig) and an alpha value of about 55 is used. The product of the isomerization process still contains waxy species and needs to be further dewaxed to reach the target pour point. The second stage dewaxing employs either solvent dewaxing (where the removed wax is recycled to the isomerization stage to increase yield) or catalytic dewaxing. Catalysts that can be used in the second stage are ZSM-5, ZSM-22, ZSM-23 and ZSM-35. In order to maintain the yield and viscosity index, the second stage dewaxing catalyst must have similar selectivity to solvent dewaxing. U.S. Pat. No. 4,919,788 also teaches a two-stage dewaxing process in which a waxy feed is partially dewaxed by isomerization using a noble metal-containing silica Y or beta catalyst. In that example, 10030 kPa_aA mildly acidic zeolite beta catalyst with a pressure of less than 55 and an alpha value of 55 is disclosed. This product is then dewaxed to the desired pour point using either solvent dewaxing or catalytic dewaxing. High shape selective dewaxing catalysts such as ZSM-22 and ZSM-23 are suitable catalysts.
US Patent Application No. 08 / 017,949 discloses a two-stage hydrocracking / hydroisomerization process. In the first stage, a bifunctional catalyst comprising a metal hydrogenation component supported on an amorphous acidic support is used. In the second stage, hydroisomerization is carried out with zeolite beta. Subsequent dewaxing is optional but recommended. Either solvent dewaxing or catalytic dewaxing may subsequently be used to obtain the target viscosity index and pour point.
In US patent application Ser. No. 08 / 017,955, a petroleum wax feedstock is hydroisomerized using a low acidity noble metal-containing zeolite catalyst. Paraffins present in the feedstock are selectively converted to isoparaffins with a high viscosity index but a low pour point, so that the final lubricating oil product exhibits good viscosity characteristics with subsequent minimal dewaxing Is manufactured. This process, carried out under high pressure, is very useful for improving waxy feedstocks such as crude wax containing aromatic content exceeding about 15% by weight to high viscosity index lubricants with high single flow yield. The need for product dewaxing is limited.
US Pat. No. 5,302,279 (and similar European patent application EP 464 547 A1) teaches the use of low acidity zeolite beta to isomerize and dewax furfural extracted oil (raffinate). It has been demonstrated in the examples that lower acidity catalysts show improved selectivity than high acidity catalysts.
US Pat. No. 5,282,958 shows improved isomerization selectivity of n-hexadecane using small pore size single pore zeolites, but all of the indicated crystal sizes are very small and are in the field of catalyst production. It is inconsistent with measurements measured by other persons skilled in the art. Furthermore, the constrained intermediate pore zeolites such as ZSM-22 and ZSM-23 used in this patent cannot access the catalyst framework as easily as other intermediate and large pore molecular sieves. The molecular reaction of the lubricant species appears to occur near the hole inlet portion of the intermediate hole catalyst. The crystal size of ZSM-22 or ZSM-23 does not appear to affect the isomerization selectivity as strongly as the less restrictive pore structure catalyst.
Summary of the Invention
The present invention uses a large pore molecular sieve having a small crystal size (crystal size or crystal diameter) to isomerize and dewax the waxy feedstock to produce a high quality, high viscosity index lubricant base stock. Includes methods. Large pore molecular sieves that can be used in the present invention are defined as having a constraint index of less than 1 and include, for example, zeolite beta, mordenite and Y. Large pore molecular sieves have an accessible pore structure for forming highly branched paraffins from waxy feedstocks, particularly feedstocks containing high molecular weight molecular species. Such branched paraffins have a high viscosity index and a low pour point. Since isomerization occurs in the pores of the catalyst, the small crystal size allows branched paraffins to diffuse easily from the pores of the zeolite without decomposition, thereby providing a high lubricant yield.
The present invention involves treating a waxy hydrocarbon feedstock with an isomerization catalyst that converts waxy species into branched paraffins. The formation of this branched paraffin having a high viscosity index and a low pour point results in a lubricant base stock exhibiting excellent quality.
The feedstock used in the present invention contains at least 20% by weight, preferably more than 30% wax. More preferably, the feedstock contains more than 50% wax. The feedstock may be pretreated prior to isomerization to remove nitrogen and sulfur containing species and reduce its aromatic content. The untreated or pretreated feedstock is contacted with a precious metal-containing low acidity large pore molecular sieve, thereby isomerizing the majority of the wax in the feedstock to produce the species typically contained in the lubricant basestock component. Form. A large pore catalyst is defined as a catalyst having at least one pore containing an oxygen 12-membered ring. Isomerization is typically hydrogen partial pressure from 4238 (600 psig) to 20786 kPa_a(3000 psig). The spilled oil from the isomerization may be further hydrotreated to remove the remaining aromatics. The zeolite beta catalyst studied in the examples of the present invention has a crystal diameter of less than 0.1 microns for maximizing the relative rate of isomerization to cracking. In small diameter crystals, the isomerized species can easily diffuse out of the catalyst skeleton, thereby reducing the potential for its decomposition. The prior art demonstrates that lower acidity catalysts show improved selectivity than high acidity catalysts. Combining high metal activity with low zeolite acidity is necessary for high isomerization selectivity, but does not guarantee such selectivity. The crystal size of certain molecular sieves was found to be an important factor affecting isomerization selectivity. Large crystals provide a longer diffusion path for the isomerized species to flow out of the skeleton, thereby increasing the likelihood that the isomerized molecule will decompose in the skeleton. The invention described in detail herein provides the selectivity advantage of isomerizing a waxy feedstock, such as crude wax, with a small crystal, low acidity zeolite beta catalyst.
In the present invention, the waxy species is selectively isomerized into a lubricating oil having a high viscosity index using zeolite beta supporting a noble metal such as platinum. The catalyst has a high isomerization selectivity, a moderate level of resistance to sulfur and nitrogen and an accessible pore structure that allows for the conversion of bulky waxy molecules. Platinum-supported zeolite beta has low zeolite acidity, high metal dispersibility, and optimum selectivity even when the crystal diameter is small.
Description of drawings
The figure compares the selectivity of wax isomerization for two low acidity silica-bound zeolite beta catalysts supported on platinum. One catalyst has a small crystal diameter and the other catalyst has a large crystal diameter.
Detailed explanation of the invention
In accordance with the method of the present invention, a relatively high wax content feedstock is converted to a high viscosity index lubricating oil by hydroisomerization using a low acidity zeolite hydroisomerization catalyst of small crystal size. A subsequent dewaxing step may be required to remove residual wax from the isomerization step. The products of the present invention are characterized by having a good viscosity characteristic exhibiting a high viscosity index, typically at least 140 (pour point-17.78 ° C (0 ° F)), usually a viscosity index of 143-147.
Feedstock
The process of the present invention can be practiced with a wide range of mineral oil-derived feedstocks to produce a range of lubricating oil products with good performance characteristics. Such properties include low pour point, low cloud point and high viscosity index. Product quality and product yield depend on the feed quality and the adaptability of the feed to the treatment with the catalyst of the present invention. High viscosity index products are obtained by using preferred wax feeds such as crude wax, waxy lower oil, deoiled wax, or vacuum distillate derived from waxy crude oil. Wax produced by the Fischer-Tropsch process of synthesis gas can also be used as a feedstock. Products with a low viscosity index can also be obtained from other feedstocks with a low initial content of waxy components.
The feedstock that can be used must have an initial boiling point that is not lower than the initial boiling point of the desired lubricating oil. The typical initial boiling point of the feedstock exceeds 343 ° C (650 ° F). Such feedstocks that can be used include vacuum gas oil, other high boiling fractions, such as distillate from vacuum distillation of atmospheric residual oil, residual oil from solvent extraction of this distillate, hydrogen It includes waxes from solvent dewaxing of hydrocracked, distillate vacuum oil, extracted residue and hydrocracked product.
The feedstock may require pretreatment before it can be processed satisfactorily in the hydroisomerization process. A generally necessary pretreatment step is the removal of low viscosity index components such as aromatic and polycyclic naphthenes and components containing nitrogen and sulfur.
A pretreatment step suitable for preparing a feedstock for hydroisomerization is the removal of aromatics and other low viscosity index components from the original feedstock. Hydroprocessing is particularly effective at high hydrogen pressures effective for aromatic saturation, eg 5600 kPa._aPretreatment effective at (800 psig) or higher pressure. Mild hydrocracking can also be used as a pretreatment if desired and is preferred for the present invention. Example 3 below describes the hydrocracking conditions used in the present invention to prepare a feedstock for the dewaxing process. 6996kPa_aA pressure in excess of (1000 psig) is preferred for the hydrocracking process. As shown in Table 6 below, nitrogen-containing species and sulfur-containing species are removed by hydrogenolysis, and the aromatic content decreases. The hydrocracking in this example slightly changed the boiling range of the feedstock so that it boiled in a lower range. Commercial catalysts such as alumina-supported fluorinated nickel-tungsten (NiWF / Al₂O_Three) May be used for hydrocracking pretreatment.
Preferred gas oil and vacuum distillate feedstocks are feedstocks having a high wax content as measured by ASTM D-3235, preferably greater than 30 wt%, more preferably greater than 50 wt%. This type of feedstock includes oils from Southeast Asia and China. Indonesian Minas gas oil is such a feedstock. These feedstocks usually have a high paraffin content (measured by conventional analytical methods for paraffins, naphthenes and aromatics). Typical feedstock characteristics of this type are described in US patent application Ser. No. 07 / 017,955.
As noted above, the preferred feedstock wax content is high and is generally at least 30% by weight (measured by ASTM Test D-3235) prior to pretreatment. The wax content prior to pretreatment is more typically at least 60-80% by weight with the balance being occluded oil containing isoparaffins, aromatics and naphthenes. Such waxy high paraffin wax raw materials usually have a low viscosity. This raw material contains a relatively small amount of aromatics and naphthenes despite its melting point and pour point which would otherwise be unacceptable as a lubricating oil due to its high content of waxy paraffins. Because there is not. The wax feed is further described in US Patent Application No. 07 / 017,955.
The most preferred type of wax feed is crude wax (see Table 2 below). Crude wax is a wax product obtained directly from solvent dewaxing processes such as MEK / toluene, MEK / MIBK or propane dewaxing processes. Crude wax is a solid or semi-solid product that mainly contains occluded oils with high waxy paraffins (mostly n- and monomethyl paraffins), while crude wax can be used as is or occluded. It can also be subjected to an initial deoiling step under normal conditions for removal. Removing the occluded oil yields a harder and more paraffinic wax that can be used as a feedstock. A by-product of the deoiling process is called waxy lower oil and may also be used as a feedstock for the process of the present invention. Wax sewer oil contains most of the aromatics present in the original crude wax and contains most of its heteroatoms along with these aromatics. Crude wax and waxy oil typically require pretreatment prior to catalytic dewaxing. The oil content of the deoiled wax is very low, and in order to measure this with good reproducibility, it is necessary to measure the oil content by the method of ASTM D721. This is because D-3225 tends to be less reliable at an oil content of less than about 15% by weight.
Some representative wax compositions are shown in Table 1 below.

A typical crude wax feed has the composition shown in Table 2 below. This crude wax was obtained by dewaxing 65 cSt (300 SUS) neutral oil obtained from Arabite crude oil at 40 ° C. with solvent (MEK).

Another coarse wax suitable for use in the present invention has the characteristics shown in Table 6 shown as part of Example 3 below. This wax is prepared by solvent dewaxing of heavy neutral furfural extracted oil. As explained above, hydrocracking may be employed to prepare crude wax for use in hydroisomerization.
Hydrocracking process (non-essential process)
If hydrocracking is employed as a pretreatment step, it is amorphous to promote saturation and ring-opening of low quality aromatic components in the feedstock so as to produce a relatively high paraffinic hydrocracking product. It is preferred to use a bifunctional catalyst. Hydrocracking is carried out at high pressures favoring aromatic saturation, but the conversion of its boiling range is kept at a relatively low level, thereby minimizing the decomposition of the saturated components of the feedstock and aromatic components. Minimize the degradation of the product obtained from the saturation and ring opening. To be consistent with the purpose of such a process, the hydrogen pressure in the hydrocracking step is at least about 5500 kPa._a(800 psig), usually 6900 (1000 psig) to 20700 kPa_aIn the range of 3000 psig. Generally at least 10500kPa_aA hydrogen partial pressure of (1500 psig) is best for achieving a high level of aromatic saturation. At least about 178n.l.l.^-1(1000 SCF / Bbl), preferably 900 (2000 SCF / Bbl) to 1800 n.l.l.^-1A hydrogen circulation rate in the range of (8000SCF / Bbl) is suitable.
In the hydrocracking process, products boiling below the lube oil boiling range, typically 345 ° C- (650 ° F-) production, to maintain the desired high single stream yield characteristic of the present invention. Conversion of the feedstock to the product is limited to 50 wt% or less of the feedstock, usually 30 wt% or less. The actual conversion rate depends on the quality of the feedstock, and the crude wax feedstock has a lower conversion rate than petrolatum (amorphous wax) which requires the removal of lower quality polycyclic components. It ’s enough. In the case of the crude wax material obtained from the dewaxing of the neutral raw material, the conversion rate to 345 ° C- (650 ° F-) product does not actually exceed 10-20% by weight. Typically, it is 5 to 15% by weight. Since petrolatum raw materials typically contain more low quality components, their conversion may be higher. For petrolatum feedstocks, the hydrocracking conversion is typically 15-25% by weight to produce high viscosity index products. The conversion can be maintained at a desired value by temperature control in the hydrocracking stage. Such temperatures are 315-430 ° C (600-800 ° F), more typically about 345-400 ° C (650-750 ° F). Changes in space velocity can also be used to control severity, but in practice they are not common due to mechanical constraints on the system. Usually space velocity is 0.25 ~ 2LHSV, hr^-1Generally, it is 0.5 to 1.5 LHSV.
A feature of the hydrocracking operation is the use of a bifunctional catalyst. Generally speaking, such a catalyst contains a metal component that promotes the desired aromatic saturation reaction and is usually a base metal that combines an iron group (Group VIII) metal and a Group VI B metal. A combination of That is, a base metal such as nickel or cobalt is used in combination with molybdenum or tungsten. A preferred combination is nickel / tungsten. This is because this combination is very effective in promoting the desired aromatic hydrocracking reaction. Precious metals such as platinum or palladium can also be used because they have good hydrogenation activity in the absence of sulfur, but are usually less preferred. The amount of metal present on the catalyst is the usual amount for this type of lube hydrocracking catalyst, generally 1 to 10% by weight Group VIII metal and 10 to 30 Group VI metal, based on the total weight of the catalyst. % By weight. When noble metal components such as platinum or palladium are used in place of base metals such as nickel or cobalt, these noble metals exhibit higher hydrogenation activity and may be of relatively small amounts, typically about 0.5 to 5% by weight is sufficient. The metal can be incorporated in any suitable manner, such as by forming a porous support into particles of the desired size and then impregnating the support or adding it to a gel of support material prior to firing. Can do. Addition to the gel is a preferred method when relatively large amounts of metal components are added, such as 10% or more by weight of Group VIII metal and about 20% or more by weight of Group VI metal. These methods are ordinary methods and are used for the production of lubricating oil hydrocracking catalysts.
The metal component of the catalyst is generally supported on a porous amorphous metal oxide support and alumina is preferred for this purpose, although silica-alumina can also be used. Other metal oxide components may also be present in the support, but their presence is somewhat undesirable. In order to match the conditions of the lube oil hydrocracking catalyst, the support is sufficient for the relatively bulky components in the high boiling feedstock to enter the catalyst's internal pore structure where the desired hydrocracking reaction takes place. It must have a pore size and distribution. In this regard, the catalyst usually has a minimum pore size of about 50 mm. That is, about 5% or more of the holes have a hole diameter of less than 50 mm, and the majority of the holes have a diameter of 50 to 400 mm (a hole not exceeding 5% has a hole diameter of more than 400 mm). Preferably, no more than about 30% of the pores have a pore size of 200-400 mm. Suitable catalysts for hydrocracking have at least 60% of their pores in the range of 50-200 mm. The pore size distribution and other properties of some representative lube hydrocracking (LHDC) catalysts suitable for use in hydrocracking are shown in Table 3 below.

If necessary to obtain the desired conversion, improve the catalyst performance with fluorine by introducing fluorine into the catalyst during catalyst preparation or by hydrocracking in the presence of a fluorine compound added to the feedstock. Can do. Fluorine-containing compounds can be prepared at the time of preparation with suitable fluorine compounds such as ammonium fluoride (NH_FourF) or ammonium difluoride (NH_FourF.HF) can be incorporated into the catalyst by impregnation, but of these ammoniums, the latter is preferred. The amount of fluorine contained in the fluorine-containing catalyst is usually about 1 to 10% by weight, preferably about 2 to 6% by weight, based on the total weight of the catalyst. Fluorine can be incorporated by adding a fluorine compound to the metal oxide support gel during catalyst preparation or by impregnating the gel after drying or calcination to form catalyst particles. As previously described, if the catalyst contains a relatively large amount of fluorine and a large amount of metal, the metal and fluorine compound may be incorporated into the metal oxide gel to form the final catalyst particles prior to drying and calcination of the gel. preferable.
Also, catalytic activity can be maintained at a desired level by fluorination in situ (in the system), for example by adding a fluorine compound to the stream passing over the catalyst at this stage of the operation. The fluorine compound can be continuously or intermittently added to the feedstock. Alternatively, the initial activity can be achieved by flowing the fluorine compound over the catalyst in the absence of the feedstock, for example, in a hydrogen stream. It is also possible to carry out the hydrogenation step and thereby increase the fluorine content in the catalyst before the actual hydrocracking starts. Such in situ fluorination of the catalyst is preferably performed prior to operation such that the fluorine content is about 1-10%, after which the fluorine is reduced to a maintenance level sufficient to maintain the desired activity. Can be made. Suitable compounds for in situ fluorination are orthofluorotoluene and difluoroethane.
The metal present on the catalyst is preferably used in the form of sulfides, so that the catalyst must be presulfided before the start of hydrocracking. Sulfurization is an established technique, typically performed by contacting the catalyst with a sulfur-containing gas, usually in the presence of hydrogen. For this purpose, a mixture of hydrogen and hydrogen sulfide, carbon disulfide or a mercaptan (eg butyl mercaptan) is common. The presulfiding treatment can also be carried out by contacting the catalyst with hydrogen and a sulfur-containing hydrocarbon oil such as sour kerosene or light oil.
Hydroisomerization
Paraffinic components present in the original wax feed have a high viscosity index, but their pour point is relatively high. Accordingly, the purpose of the method of the present invention is to provide selective conversion of waxy species while minimizing conversion of more branched species as lubricating oil components. Wax conversion preferentially causes isomerization, thereby producing more branched species with lower pour and cloud points. Some decomposition occurs with isomerization, and the extent of this decomposition varies with the conversion of wax.
Hydroisomerization catalyst
The catalyst used in the hydroisomerization of the present invention is a highly selective catalyst that isomerizes waxy linear or nearly linear paraffins to isoparaffinic products having low wax properties. This type of catalyst includes a metal component supported on a porous carrier having a large pore size that is bifunctional in nature and relatively low in acidity. Acidity is kept at a low level to reduce conversion to products having boiling points outside the lube oil boiling range during this stage of operation. Generally speaking, the catalyst should have an alpha value of less than 30 prior to the addition of the metal, with a preferred alpha value of less than 20 (see Example 1).
The alpha value is an approximate indicator of the catalytic cracking activity of the catalyst compared to the standard catalyst. In the alpha test, a standard catalyst with an alpha value of 1 (rate constant = 0.016 sec)^-1) Relative to the test catalyst (unit time and n-hexane conversion rate per unit volume of catalyst). The Alpha test is described in US Pat. No. 3,354,078, and J. Catalysis, Vol. 4, pp. 527 (1965); Vol. 6, pp. 278 (1966); 1980). These are referenced for a description of the test method. The experimental conditions of the test employed to determine the alpha values presented herein include a constant temperature of 538 ° C. and a variable flow rate described in Journal of Catalysis Vol. 61, page 395 (1980).
Hydroisomerization catalysts include large pore molecular sieves, generally zeolites or silica / aluminophosphates. The large pore molecular sieve is supported on a porous binder. Large pore zeolites usually have at least one pore path consisting of a 12-membered oxygen ring. Large pore zeolites typically have at least one channel with a major dimension greater than 7 mm. Zeolite beta, Y and mordenite (mordenite) are examples of large pore zeolites.
The catalyst of the present invention has a crystal diameter of less than 0.1 microns to maximize the relative ratio of isomerization: decomposition. With small diameter crystals, the isomerized species can easily diffuse out of the crystal structure, thereby reducing the potential required for its decomposition.
A preferred hydroisomerization catalyst uses zeolite beta. This is because this zeolite beta has been shown to have significant activity against paraffin isomerization in the presence of aromatics, as disclosed in US Pat. No. 4,419,220. The low acidity form of zeolite beta is obtained by synthesizing a zeolite with a high silica content form, for example a zeolite with a silica: alumina ratio of about 500: 1 or more, more simply a zeolite with a low silica / alumina ratio is desired. Can be obtained by steaming to an acidity level of. Zeolite beta can also be obtained by extraction with an acid, such as a carboxylic acid, as disclosed in US Pat. No. 5,200,168. US Pat. No. 5,164,169 discloses the production of high silica zeolite beta using a chelating agent such as a quaternary alkenolamine in the synthesis mixture. U.S. Pat. No. 3,308,069 discloses the synthesis of zeolite beta having a crystal size of 0.01 to 0.05 microns. A catalyst having a crystal diameter in this range is used in the present invention. The crystal diameter of the present invention does not exceed 0.1 microns, and a crystal diameter of 0.01 to 0.05 microns is preferable.
Most preferred zeolites are heavily steamed and the framework has a silica / alumina ratio of 200: 1 or more, preferably 400: 1 or more.
Steam treatment conditions should be adjusted to achieve the desired alpha value in the final catalyst, typically at a temperature of about 427 ° C. to 595 ° C. (800 to about 1100 ° F.) with a 100% steam atmosphere. Use. Typically, the steam treatment is carried out at a temperature of 538 ° C. (1000 ° F.) or higher for about 12 to 120 hours, typically about 96 hours, to reduce the acidity as desired.
Another method for producing a low acidity zeolite beta catalyst is to replace a portion of the zeolite framework aluminum with other trivalent atoms, such as boron, thereby lowering the lower intrinsic level of acid activity of the zeolite. Is obtained. Preferred zeolites of this type are those containing boron in the framework. Usually, boron is added to the zeolite framework before the addition of other metals. In this type of zeolite, the framework is mainly composed of silicon that is tetrahedrally coordinated and bonded together by oxygen bridges. A small amount of element (aluminum in the case of aluminosilicate zeolite beta) also coordinates and forms part of the framework. In addition, the zeolite may contain a substance that does not form a part of the framework constituting the characteristic structure of the zeolite in the pores of the structure. As used herein, the term “framework” boron refers to a substance in the framework of the zeolite that contributes to the ion exchange capacity of the zeolite, and is a substance that exists in the pores and affects the overall ion exchange capacity of the zeolite. Used to distinguish from no substance. Zeolite beta has a constraint index of 0.60 to 2.0 at a temperature of 316 ° C to 399 ° C, but a constraint index of less than 1 is preferred.
A method for producing a high silica content zeolite containing framework boron is disclosed and known, for example, in US Pat. No. 4,269,813. A process for making framework boron-containing zeolite beta is disclosed in US Pat. No. 4,672,049. As disclosed therein, the amount of boron contained in the zeolite can be achieved by incorporating various amounts of boron ions into the zeolite forming solution, for example, by varying the amount of boric acid relative to the silica and alumina composition. Can be changed. Reference is made to these disclosures relating to a description of the process for producing the zeolite.
The low acidity zeolite beta catalyst should contain at least 0.1 wt%, preferably at least 0.5 wt% framework boron. Before adding other metals, boron may be added to the skeleton. In general, the maximum amount of boron can be about 5% by weight of the zeolite, and in most cases not more than 2% by weight. The framework can usually contain some alumina. The silica: alumina ratio can usually be at least 30: 1 in the synthesized zeolite state. A preferred boron-substituted zeolite beta catalyst contains at least 1 wt.₂O_ThreeThe boron-containing zeolite contained as is steamed to produce a final alpha value of about 20 or less, preferably 10 or less.
Characteristic
Acidity is measured with ammonia (NH_Three), And can be reduced by introducing nitrogen compounds such as organic nitrogen compounds. However, the total nitrogen content in the feedstock should not exceed 100 ppm and is preferably at least less than 20 ppm. The catalyst may also include a metal that reduces the number of strong acid sites on the catalyst to improve the selectivity of the isomerization reaction over the cracking reaction. Suitable metals for this purpose are those belonging to the group IIA metals such as calcium and magnesium.
The zeolite can be a composite containing a matrix material to form the final catalyst, for which purpose conventional matrix materials with very low acidity such as alumina, silica-alumina, silica, etc. are suitable. However, alumina such as alpha boehmite (Alfalumina monohydrate) can also be used as long as it does not substantially affect the acidity of the matrixing catalyst. Zeolites are usually complexed in a matrix amount of zeolite: matrix weight ratio of 80:20 to 20:80, typically 80:20 to 50:50. The composite can be carried out in a conventional manner, for example by kneading the materials and then extruding the desired final catalyst particles. A suitable extrusion process for zeolites containing silica as a binder is disclosed in US Pat. No. 4,582,815. When the catalyst is to be steamed to achieve the desired low acidity, the steaming is performed after blending the catalyst with a binder as in the conventional method. A preferred binder for the steam treatment catalyst is alumina.
The hydroisomerization catalyst may also include a metal component that proceeds through the unsaturated transition species and promotes the desired hydroisomerization reaction requiring the intervention of a hydro-dehydrogenation component. For this reason, in order to maximize the isomerization activity of the catalyst, a metal exhibiting a strong hydrogenation function is preferable, and platinum and other noble metals such as rhenium, gold, palladium and the like are preferable. The amount of the noble metal hydrogenation component is typically 0.1 to 5% by weight, usually 0.1 to 2% by weight of the total amount of the catalyst. Platinum can be incorporated into the catalyst by conventional methods, including ion exchange with complex platinum cations such as platinum tetraamine and impregnation with a soluble platinum compound, eg, a platinum tetraamine salt such as tetraamine platinum chloride. The catalyst is subjected to a final calcination treatment under normal conditions to bring the noble metal into its reduced form and to obtain the mechanical strength required for the catalyst. The catalyst may be subjected to the presulfidation treatment for hydrocracking pretreatment catalyst before use.
Hydroisomerization conditions
The conditions of the hydroisomerization process (also called isomerization process) are waxy, linear and nearly linear paraffinic components in the waxy feedstock with a low but high viscosity index and a relatively high viscosity index. Adjusted to achieve the goal of isomerization to low pour point isoparaffinic material. This object is achieved while minimizing the conversion to products in the non-lubricating oil boiling range (substances of 345 ° C .- (650 ° F.)). Because the catalysts used for hydroisomerization have low acidity, conversion to low boiling products is usually at a relatively low level, and the choice of suitable severity limits process operation over cracking. It can be optimized for isomerization. At a normal space velocity of about 1, using a platinum / zeolite beta catalyst with an alpha value of less than 20, the hydroisomerization temperature typically ranges from about 300 to 415 ° C. (about 570 to about 780 ° F.). And the conversion to 345 ° C .- (650 ° F.) product is typically about 5-30% by weight of the waxy feedstock, more typically 10-25% by weight.
Hydroisomerization is operated at a hydrogen partial pressure (reactor inlet) of at least 5516 kPaa (800 psig), usually 5167-20786 kPaa (800-3000 psig), most usually 5516-17340 kPaa (800-2500 psig). Hydrogen circulation rate is usually about 90-900n.l.l.^-1(500 to 5000 SCF / Bbl). Aromatic components present in the original feedstock undergo some saturation reaction in the presence of the noble metal hydrogenation component on the catalyst, so that even if the desired isomerization reaction is in a hydrogen balance state, Consumed in hydroisomerization. For this reason, the hydrogen circulation rate may need to be adjusted according to the aromatic content of the feedstock and the temperature used for hydroisomerization. This is because higher temperatures involve higher levels of cracking and the resulting higher levels of olefin production, some of which are in the lube oil boiling range, and this It is therefore necessary to ensure the stability of the product by saturation. At least 180n.l.l.^-1A hydrogen circulation rate of (1000 SCF / Bbl) usually provides sufficient hydrogen to compensate for the desired hydrogen consumption and to compensate for the decrease in catalyst aging rate.
Rapid cooling between the beds is desirable to maintain process temperature. Cooled hydrogen is commonly used as the quenching agent, but liquid quenching agents, usually recycled products, can also be used.
Dewaxing
Depending on the wax content of the feedstock, a final dewaxing step may be required to achieve the desired pour point. It is a prominent feature of the present invention that the required degree of dewaxing is relatively small. Typically, the loss during the final dewaxing step can be 15-20% by weight or less of the feedstock in the dewaxing device. Either catalytic dewaxing or solvent dewaxing can be used at this point, and if a solvent dewaxing device is used, the removed wax is recycled to the hydroisomerization and passed through this isomerization process again. May be. The need for product dewaxing by a dewaxing device is relatively small, and in this respect the present invention is significant compared to methods using a single amorphous catalyst that requires a significant degree of dewaxing. Provide improvements. Due to the high isomerization selectivity of the zeolite catalyst, it is possible to achieve a single-flow wax conversion that is typically about 80% higher than the 50% of the above-mentioned amorphous catalyst method. Is significantly improved.
The shape selective dewaxing catalyst can be used instead of the solvent dewaxing process. This catalyst removes slightly branched chain waxy paraffins with n-paraffins, while leaving more branched chain isoparaffins in the process stream. The shape selective catalytic dewaxing process uses a catalyst that is more highly selective for n-paraffins and slightly branched chain paraffins than the isomerization catalyst zeolite beta. The selective catalytic dewaxing process is performed as described in US Pat. No. 4,919,788 (see this US patent disclosure for a description of this stage). The catalytic dewaxing step of the process of the present invention is preferably carried out using a constrained shape selective dewaxing catalyst based on a constrained intermediate pore size crystalline material such as aluminosilicate. The constrained intermediate pore size crystalline material has a cross-hole with an 8-membered ring with at least one oxygen 10-membered ring channel. ZSM-23 is a suitable zeolite for this purpose, but other highly shape-selective zeolites such as ZSM-22 or synthetic ferrierite ZSM-35 can be used, especially for lighter materials. Silica aluminophosphates such as SAPO-11 and SAPO-41 can also be used as selective dewaxing catalysts.
A suitable catalyst for use as a dewaxing catalyst is a relatively constrained intermediate pore size zeolite. Such suitable zeolites have a restraining index of 1 to 12 as measured by the method described in US Pat. No. 4,016,218. These preferred zeolites are also characterized by specific sorption characteristics associated with their relatively constrained diffusion characteristics. This sorption property is that shown in US Pat. No. 4,810,357 for zeolites such as zeolites ZSM-22, ZSM-23, ZSM-35 and ferrierite. These zeolites have pore openings that provide a specific combination of sorption characteristics as follows:
(1) P / P_oN-hexane: o-xylene sorption ratio (based on volume%) of greater than about 3, measured at = 0.1 and temperatures of 50 ° C. (n-hexane) and 80 ° C. (o-xylene), and
(2) K exceeding about 2 measured at 538 ° C (1000 ° F)_3MP/ k_DMBFrom a mixture of n-hexane / 3-methylpentane / 2,3-dimethylbutane (weight ratio 1/1/1) with a rate constant ratio of 2,3- Ability to selectively decompose 3-methylpentane (3MP) over dimethylbutane (DMB).
Formula: P / P₀Is consistent with its usual meaning as described in the literature [“The Dynamical Character of Adsorption” (JHdeBoer) 2nd edition, Oxford University Press (1968)), and the sorption quality at the sorption temperature. Partial pressure: Relative pressure defined as the ratio of vapor pressure of sorbate. Speed constant ratio, k_3MP/ k_DMBIs determined from the first order kinetics according to the following formula, according to the usual method:
k = (1 / T_c) Ln (1 / 1−ε)
Where k is the rate constant of each component, T_cIs the contact time, and ε is the conversion of each component.
Zeolites that meet these sorption conditions include natural zeolite ferrierite and synthetic zeolites ZSM-22, ZSM-23 and ZSM-35. These zeolites are at least partially in the acid or hydrogen form when used in the process of the present invention.
The preparation and properties of zeolite ZSM-22 are described in US Pat. No. 4,810,357 (Chester), the disclosure of which is incorporated herein.
Synthetic zeolite ZSM-23 is described in U.S. Pat. Nos. 4,076,842 and 4,104,151, the disclosure of which is disclosed herein with respect to the zeolite, its preparation and properties.
A synthetic crystalline material of intermediate pore size called “ZSM-35” (“Zeolite ZSM-35” or simply “ZSM-35”) is described in US Pat. No. 4,016,245, with disclosure of this zeolite and its preparation. It shall be described in this specification. The synthesis of SAPO-11 is described in US Pat. Nos. 4,943,424 and 4,440,871. The synthesis of SAPO-41 is described in US Pat. No. 4,440,871.
Ferrierite is a natural mineral described in the literature (see, eg, DWBreck, ZEOLITE MOLECULAR SIEVES, John Wiley and Sons (1974) 125-127, 146, 219 and 625) and is disclosed herein with disclosure about this zeolite. It is said that.
The dewaxing catalyst used for shape selective catalytic dewaxing includes a metal hydrogenation-dehydrogenation component. Although this component may not be strictly necessary to promote the selective cracking reaction, the presence of this component is desirable for the promotion of certain isomerization reactions that contribute to the synergism of the two-catalyst dewaxing system. There was found. The presence of the metal component leads to an improvement of the product, in particular an improvement and stability of the viscosity index and a delayed contribution of catalyst aging. Shape selective catalytic dewaxing is usually carried out under pressure in a hydrogen atmosphere. The metal is preferably platinum or palladium. The amount of the metal component can typically be 0.1 to 10% by weight. Matrix materials and binders can be used as needed.
Shape selective dewaxing using a highly constrained high shape selective catalyst can be carried out in the same conventional manner as other catalytic dewaxing methods, such as those described above for the first isomerization stage. See US Pat. No. 4,919,788 for a more detailed description of the shape selective catalytic dewaxing process.
The degree of conversion to low boiling point species in the dewaxing process can be changed at this point according to the desired degree of dewaxing, ie the difference between the target pour point and the effluent pour point from the isomerization process. . The degree of conversion can also depend on the selectivity of the shape selective catalyst used. At lower product pour points, using a relatively low selectivity dewaxing catalyst incurs higher conversion and corresponding higher hydrogen consumption.
After reducing the pour point of the oil to a desired value by selective dewaxing, the dewaxed oil is subjected to a treatment such as hydrotreating to remove colored bodies and a lubricating oil product having desired characteristics Can be manufactured. Also, fractional crystallization can be used to remove light oils and meet volatility standards.
Product
The product according to the process of the invention is a material with a high viscosity index and a low pour point, obtained in excellent yield. In addition to having excellent viscosity properties, the product of the present invention is very stable to oxidative, thermal and ultraviolet radiation. With a wax feed suitable for the process, a viscosity index value in the range of 130-150 is typically obtained, and a value of at least 140 is at least 50% by weight, usually at least 60% based on the original wax feed. % Product yield can easily be achieved.
Example
Example 1
65 wt% zeolite beta and 35 wt% silica (SiO₂) Was first extruded to produce a catalyst containing low acidity zeolite beta. The zeolite beta used for this production is SiO₂/ Al₂O_ThreeThe ratio is 600 and the average crystal size is 1-3 microns (measured with a scanning electron microscope (SEM)) (see US Pat. Nos. 5,232,579, 5,164,169, and 5,164,170 for details of this synthesis). A mixture of zeolite beta and silica was mixed with an aqueous caustic solution to form a paste and then extruded according to standard methods for catalyst preparation. Extrudates are dried at 250 ° F for 8 hours and then 5v / v 1N NH_FourNO_ThreeContact with the solution reduced its sodium content. The sodium reduced extrudate is then heated to 482 ° C. (900 ° F.) under a nitrogen atmosphere, held at this temperature for 3 hours, and then exposed to air at 538 ° C. (1000 ° F.) for 6 hours to form zeolite beta. The organic compound used in the production of was decomposed. This catalyst is then added to 101 kPa against 100% steam._aExposure at (0 psig) for a sufficient time (24 hours) reduced its alpha activity value to less than 15.
This steam treated deactivated zeolite beta containing material was then replaced by an aqueous solution of tetraamine platinum chloride dihydrate maintained at pH 7-8. The platinum exchanged catalyst was washed with water to remove chloride, then heated to 349 ° C. (660 ° F.) in air and held at this temperature for 3 hours. The final catalyst contains 0.6% by weight of platinum and has the properties shown in Table 4 below.

Example 2
65 wt% zeolite beta and 35 wt% silica (SiO₂) Was first extruded to produce a catalyst containing zeolite beta. The zeolite beta used for this production is SiO₂/ Al₂O_ThreeThe average crystal size was less than 0.05 microns (measured with scanning electron microscope (SEM)) and was synthesized according to the standard method for MIDW Grade Zeolite Beta. A mixture of zeolite beta and silica was mixed with an aqueous caustic solution to form a paste and then extruded according to standard methods in the catalyst field. The extrudate was dried at 121 ° C. (250 ° F.) for 8 hours. The sodium-containing extrudate was then heated to 482 ° C. (900 ° F.) under a nitrogen atmosphere, held at this temperature for 3 hours, and then exposed to 538 ° C. (1000 ° F.) air for 6 hours to produce zeolite beta. The organic compound used for the production was decomposed. The catalyst was then contacted with 2M aqueous oxalic acid at 71 ° C (160 ° F) for a total of 6 hours. The oxalic acid treated zeolite beta catalyst was then heated to 538 ° C. (1000 ° F.) for 2 hours. This material has an alpha value of less than 10 and a sodium content of 525 ppmw.
The oxalic acid treated zeolite beta catalyst was then replaced by an aqueous solution of tetraamine platinum chloride dihydrate maintained at pH 5-6. The platinum exchanged catalyst was washed with water to remove chloride, then heated to 349 ° C. (660 ° F.) in air and held at this temperature for 3 hours. The final catalyst contains 0.5% by weight of platinum and has the properties shown in Table 4 above.
Example 3
Crude wax obtained from 97cSt (450SUS) heavy neutral furfural extracted oil by solvent dewaxing was hydrocracked at moderate severity to reduce its sulfur and nitrogen content. The conditions of the mild hydrocracking process are 2LHSV, 404 ° C (760 ° F) and hydrogen partial pressure 13891kPa_a(2000 psig). The characteristics of the crude wax and the stripped hydrocracking products are shown in Table 5.
A mild hydrocracking process converted 16% of the crude wax feed to a product with a boiling point of less than 343 ° C. (650 ° F.) and 17% of the wax in the feed. The wax conversion and the yield of the lubricating oil are calculated by the following equations. The yield of dewaxed oil was corrected to 0 ° F. pour point for consistency.
Wax conversion = 100 × [(the wax content of the feedstock
-Wax content of reaction product) / wax content of feedstock]
Wax yield = (Yield of distillation still residue for wax feed)
× (Solvent dewaxing equipment
(Yield of oil-free wax from solvent dewaxing)
Lubricating oil yield = 100-low yield
-Conversion of 650 ° F + measured by simulated distillation

Example 4
The mild hydrocracked crude wax of Example 3 was reacted by separate experiments using the platinum / zeolite beta catalysts of Examples 1 and 2. The reaction conditions were 13891 kPa for the catalyst of Example 1._a(2000 psig) and 1 LHSV were used, and for Example 2, 1.25 LHSV was used. The severity of the reaction was changed by changing the catalyst temperature. Before introducing the liquid feed, the mixture (H₂S / H₂= 2:98 (volume%)) both catalysts were presulfided at a maximum temperature of 371 ° C (700 ° F).
The reactor effluent from these experiments was analyzed by simulated distillation to determine the conversion of 343 ° C .- (650 ° F.) product and then distilled at a nominal cut point of 343 ° C. (650 ° F.). . The wax yield, lubricating oil yield and wax conversion are calculated based on the formula of Example 3 and shown in Table 6. The figure shows the relative dependence of lubricating oil yield on the wax conversion of the two catalysts.
The low isomerization selectivity (Example 2) of the small crystal catalyst is significantly higher than that of the large crystal catalyst (Example 1). Lubricating oil yields peak at 64% for the small crystal platinum / zeolite beta (Pt / B) catalyst, but only reach 52% for the large crystal catalyst. Matching the continuous reaction system of isomerization and subsequent shape selective cracking, both catalysts give similar yields at low wax conversions (less than 40%). However, as the severity of the reaction increases, the cracking rate of the large crystal catalyst relative to the isomerization rate increases, so that at 50% wax conversion, the rate of formation of the lubricating oil by isomerization is reduced by that of the lubricating oil by cracking. Consistent with loss rate. Increasing the wax conversion beyond this point decreases the yield of the lubricating oil. In contrast, the isomerization: cracking ratio is kept high until high wax conversion is achieved for small crystal catalysts. The two reaction rates did not equal until the wax conversion reached 80%.
The actual utility of the present invention is the ability of this catalyst for selective action at high wax conversions, as well as the obvious high yields with small crystal catalysts. This capability reduces the amount of recycle of the wax and the size of the reactor required to produce a given amount of high viscosity index base stock.
The acidity of the zeolite can also play an important role in determining isomerization selectivity. Large crystal platinum / zeolite beta catalysts have higher alpha values compared to small crystal catalysts (13 vs. 8), and the observed selectivity differences between these catalysts do not appear to be primarily a function of acidity. It is. The difference in alpha value is not substantially large.

Claims (10)

Slack wax, deoiled wax, Fischer - wax from Tropsch process, petrolatum, selected from the group consisting of raffinate from solvent extraction of vacuum gas oil and vacuum distillates, Carlo which have a wax content of at least 20% A method for producing a high viscosity index (VI) lubricating oil from a hydrocarbonaceous feedstock,
A wax present in the feedstock, mainly by isomerization, in the presence of low acidity large pore molecular sieves having a crystal size of less than 0.1 microns and an alpha value of 30 or less and containing a noble metal hydrogenation component and in the presence of hydrogen. A process characterized by catalytic dewaxing of paraffins. Slack wax, deoiled wax, Fischer - wax from Tropsch process, petrolatum, selected from the group consisting of raffinate from solvent extraction of vacuum gas oil and vacuum distillates, Carlo which have a wax content of at least 20% A method for producing a high viscosity index (VI) lubricating oil from a hydrocarbonaceous feedstock,
(A) a waxy hydrocarbon feed, removing a naphthenic components and aromatic components with in contact with a catalyst comprising a metal hydrogenation component on an acidic carrier comprising the steps of hydrocracking to reduce the nitrogen content and, the step of thereby is above the viscosity index improvement, and (b) the waxy paraffins present in the feed has a presence and crystal diameter and 30 following the alpha value of less than 0.1 micron hydrogen and a noble metal in the presence of a low acid resistance of large pore molecular sieves containing hydrogenation component, the step of dewaxing contact primarily by isomerization
A method comprising the steps of: 3. A process according to claim 1 or 2 wherein the large pore molecular sieve is a zeolite beta that has been steamed and has a framework silica: alumina ratio of at least 200: 1. The method according to any one of claims 1 to 3, wherein the large pore molecular sieve has at least one oxygen 12-membered ring passage and contains 0.3 to 2 wt% platinum. The process according to any one of claims 1 to 4, wherein the isomerization is carried out under conditions comprising a hydrogen partial pressure of 4238-20786 kPaa (600-3000 psig) and a temperature of 288-427 ° C (550-800 ° F). The effluent from the process of claim 1 or step (b) of the process of claim 2 is passed through a catalyst comprising a metal hydride component on an amorphous porous support material to a hydrogen partial pressure of about 3549 to About 20786 kPaa (500 to about 3000 psig), reaction temperature about 260 to about 427 ° C. (500 to about 800 ° F.), space velocity about 0.1 to about 10 LHSV, and once-through hydrogen circulation rate about 178 to about 1780 n.ll ⁻¹ (1000 to The method according to claim 1 or 2, wherein the hydrotreating is carried out under contact conditions including about 10,000 SCF / B). The process of any of claims 1-6, wherein the effluent is further subjected to dewaxing to achieve a target pour point, the dewaxing being effected by either catalytic dewaxing or solvent dewaxing. . The effluent, after further dewaxing, is converted to a catalyst comprising a metal hydride component on an amorphous porous support material, a hydrogen partial pressure of about 3549 to about 20786 kPaa (500 to about 3000 psig), and a reaction temperature of about 260 to 427 ° C. 8. Hydrogenation by contact under conditions including (500 to about 800 ° F.), space velocity of about 0.1 to about 10 LHSV, and through-flow hydrogen circulation rate of about 178 to 1780 n ll ⁻¹ (1000 to about 10,000 SCF / B). The method described in 1. 9. A method according to any one of the preceding claims, wherein the large pore molecular sieve has a crystal size of less than 0.05 microns. The method according to any of claims 1 to 9, wherein the large pore molecular sieve comprises a boron-containing zeolite beta isomerization catalyst in which boron is present as a framework component of zeolite beta.

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