JP3661770B2 - Fuel oil for gasoline engines - Google Patents

Description

〔式中、ＢＺはベンゼン含有量、ＴＯはトルエン含有量、ＥＢはエチルべンゼン含有量、ＸＹはキシレン含有量、Ｃ₉ ⁺ Ａは炭素数９以上の芳香族分含有量（いずれも燃料油中の含有量で容量％）を示す。〕
で表される排気ガス指数Ｙが５以下、好ましくは４以下、より好ましくは3.５以下である。該指数Ｙは、燃料油がエンジンで燃焼した際に生じる排気炭化水素中に含まれるベンゼンの割合を示すものであり、各係数は、排気炭化水素中のベンゼン含有量（重量％）／燃料油中の各成分の含有量（容量％）の値である。すなわち、この値はベンゼンが最も大きく、次いでモノアルキルベンゼン、ジアルキルベンゼン、トリアルキルベンゼンと、ベンゼン環の置換基が多くなるほど小さくなる。また、パラフィン及びオレフィンはそれぞれ0.００５と極めて小さい。〔１００−（ＢＺ＋ＴＯ＋ＥＢ＋ＸＹ＋Ｃ₉ ⁺ Ａ）〕は燃料油中の芳香族分以外の成分を表す。上記式（Ｉ）で表される排気ガス指数Ｙが５を超えると、排気ガスの低公害化が充分に達せられない。なお、各芳香族分の含有量は、ガスクロマトグラフ法による燃料油の全組成分析（石油学会法ＪＰＩ−５Ｓ−９０に準拠）から算出した値である。
【０００７】
本発明の燃料油においては、（４）ベンゼン含有量が1.０容量％、好ましくは0.５容量％以下であり、かつ硫黄分が４０ｐｐｍ以下、好ましくは３０ｐｐｍ以下である。ベンゼン含有量が1.０容量％を超えると、燃料油自体が人体に悪影響を及ぼしたり、また排気ガス中のベンゼン含有量が多くなって、環境汚染をもたらすおそれが生じる。硫黄分が４０ｐｐｍを超えると、排気ガス中のＳＯ_X が増加するとともに、触媒の被毒によって三元触媒の活性が低下し、その結果排気ガス中のＮＯ_X も増加することとなる。なお、硫黄分の含有量は、ＪＩＳ Ｋ−２５４１に従って微量電量滴定酸化法により測定した値である。
さらに、本発明の燃料油においては、（５）リサーチ法オクタン価が９７〜１０２、好ましくは９８〜１０１の範囲にある。
【０００８】
本発明の燃料油は、上記（１）〜（５）の条件を満たすものであればよく、その起源については、特に制限はないが、例えば次に示すガソリン基材を用いて、該（１）〜（５）の条件を満たすように適宜配合することにより、調製することができる。該ガソリン基材としては、例えば原油の常圧蒸留によるナフサ留分を分留して得られる軽質ナフサ、接触分解法や水素化分解法などで得られる分解ガソリン、接触改質法などで得られる改質ガソリンから後述の方法でベンゼン留分を取り除いた残りの留分、オレフィンの重合により得られる重合ガソリン、イソブタンなどの炭化水素に低級オレフィンを付加（アルキル化）することにより得られるアルキレート、直鎖の低級パラフィン系炭化水素の異性化によって得られるアイソメレート、脱ｎ−パラフィン油、及びこれらの特定範囲の留分や芳香族炭化水素などが挙げられる。
【０００９】
上記改質ガソリン（ベンゼン４〜１０容量％）中のベンゼン量低減化方法としては、例えば、▲１▼接触改質装置の運転条件の変更、▲２▼原料の脱硫重質ナフサ中のＣ₆ 留分の蒸留による除去方法、▲３▼改質ガソリンからベンゼン留分を蒸留により取り除く方法、▲４▼触媒反応により、改質ガソリン中のベンゼン分を水素化処理してシクロヘキサン等に転化し、更にこれを異性化装置に導いて高オクタン価の異性体に異性化処理する方法、▲５▼触媒反応により、改質ガソリン中のベンゼン分をアルキル化し、高オクタン価のアルキル芳香族分に転化する方法、及び▲６▼上記▲２▼の方法で除去分離したベンゼン分を、エチレン等を多量に含有するＦＣＣ（流動接解分解装置）オフガスによりアルキル化して、高オクタン価のアルキル芳香族分に転化する方法などがある。
上記▲１▼の方法は、反応温度を低くする方法であるが、原料の脱硫重質ナフサ中のＣ₆ ナフテンの脱水素反応が律速であり、改質ガソリン中のベンゼン含有量を４容量％以下にするのは困難であり、また、▲２▼の方法では、原料の脱硫重質ナフサ中の軽質留分（Ｃ₆ が主体）を４５容量％程度カットしても、改質ガソリン中のベンゼン含有量は1.５容量％程度が限界である。これは、炭素数７以上の炭化水素からもベンゼンが生成するためである。したがって、改質ガソリンのベンゼン量低減化方法としては、上記▲３▼の方法が好適である。この方法は、通常第１スプリッター及び第２スプリッターを用いて、改質ガソリンからベンゼン留分を取り除く方法であり、得られる脱ベンゼン改質ガソリン中のベンゼン含有量は０〜0.５容量％程度にまで低下する。また、ベンゼン分は、精製してベンゼン製品化やシクロヘキサン，スチレンモノマー等の原料化等、石油化学原料用として利用することができる。さらに、このベンゼンをアルキル化すればトルエン，キシレン等のアルキルベンゼンに転化することができる。また、シクロヘキサンを異性化すればメチルシクロペンタンに転化することができる。
上記▲４▼及び▲５▼の方法は、触媒反応のために更に新たな処理装置の設置が必要となるが、抽出したベンゼン分の利用方策がない場合、及び該装置から得られる新規留分が、ガソリン製造基材や石油化学原料用等として利用可能な場合においては、上記▲３▼の方法に比較して更に効率的なベンゼン低減方法となり得る。
その他に、ベンゼン留分の水素化処理法やベンゼン抽出法などがある。ここでベンゼン留分の水素化処理法では、まずベンゼン先駆物質を含む留分を蒸留により分離し、残りの留分を接触改質装置にかけ、生成したリフォーメートはスプリッターへ導入してベンゼン留分を分離し、これを水素処理飽和化する。さらに三成分を再びブレンドして混合リフォーメートにする。一方、ベンゼン抽出法では、水素化脱硫ナフサを蒸留して、ｉ−Ｃ₅ 〜ｎ−Ｃ₆ 留分を分離し、７０℃⁺ 留分を接触改質装置にかけ、スプリッターでＣ₅ 留分，ベンゼントルエン留分（ＢＴ留分）及びリフォーメート留分に分離する。このうちＢＴ留分は抽出装置へ導入し、ベンゼン（Ｂ），トルエン（Ｔ）及びラフィネートに分離する。ベンゼンは石油化学原料に利用し、リフォーメート高沸点留分はそのままＣ₅ 留分，トルエン及びラフィネートと混合して混合リフォーメートにする。
【００１０】
次に、上記▲４▼の方法について、更に詳細に説明する。この方法では、改質ガソリン（リフォーメート）を蒸留してＣ₅ ，Ｃ₆ 留分を含むライトリフォーメート留分をカットした後、これを水素化処理して留分中のベンゼンをシクロヘキサンに転化し、更にこのシクロヘキサンを異性化装置に導入して、メチルシクロペンタン及びｎ−ヘキサンに開環するとともに、ｎ−ヘキサンは更に高オクタン価の異性体に変換する。この方法は、これらの諸反応を二塔式あるいは一塔式で行う二種のプロセスに大別することができる。
このうち二塔式のプロセスの概略は以下の通りである。まず、原料油と水素が熱交換器で予熱された後、加熱炉で昇温され、水素化反応塔（第１反応塔）へ導入される。水素化反応塔は発熱反応であるため触媒層は水素ガスにより冷却され、反応温度が制御される。温度上昇を抑えることにより水素化分解が抑制されるので、液収率を上げることができる。水素化反応塔から出た処理油は、ゼオライト系異性化触媒が充填されている異性化反応塔（第２反応塔）へ導入される。この第２反応塔は、第１反応塔とほぼ同じ温度で運転されることから、何ら熱交換器を必要としない。この異性化反応塔を出た反応生成物は、分離塔へ送られ、気・液分離される。水素は反応塔へリサイクルされ、液相部はスタビライザーへ送られ、オフガスが分離される。
次に、一塔式のプロセスは、水素化反応と異性化反応を同一反応塔で実施するために、温度制御は極めて細心の注意を払って行われる。冷却水素は反応塔の各段へ供給される。下流部分は上記二塔式のプロセスとほぼ同じ構成になっている。いずれの方式も通常の異性化反応に適用される反応条件（温度，圧力）は、温和な条件で行われ、いずれも接触改質において発生した水素を使用する。
上記▲４▼の方法では、二塔式や一塔式のプロセスのいずれを問わず、そこで使用される水素化反応触媒は、白金／アルミナ系であり、高活性でしかも安定性があり、液収率が高い。異性化反応触媒は、ゼオライトをベースにした触媒であり、水素化反応とほぼ同じ温度で通油されることから、熱交換や冷却システムが簡素化され、建設費が安価であって経済的であり、また温和な運転条件により、触媒寿命を延ばすことも可能である。この運転条件の一例を挙げれば、水素化反応を圧力２9.６ａｔｍ（絶対圧），入口温度１８０〜２５０℃，液時空間速度（ＬＨＳＶ）４〜６ｈｒ^-1で行い、異性化反応を圧力２9.６ａｔｍ（絶対圧），入口温度２４０〜２７０℃，液時空間速度（ＬＨＳＶ）１〜３ｈｒ^-1で行うことができる。
なお、単にベンゼン分を低減化するだけであれば、ベンゼン濃度３０容量％以下のＣ₅ 〜Ｃ₆ 留分を各種の貴金属触媒を使用して水素化処理することによって、効率よくシクロヘキサンに転化でき、副反応を極力抑制することができる。
【００１１】
続いて、上記▲６▼の方法について、更に詳細に説明する。この方法は、下記の方法Ｉと方法IIの二つに大別される。
まず方法Ｉでは、はじめにＣ₅ 以上のリフォーメート留分を蒸留によってＣ₅ 留分，ベンゼンを含む留分およびＣ₇ ⁺ 重質リフォーメートの三留分に分離する。ＦＣＣオフガスはアミン洗浄して硫化水素を除去した後、直ちにベンゼン低減化装置（例えば、モービル社製，ＭＢＲ装置）へ導入する。ＦＣＣオフガスは大部分がエチレンであるが、５〜１０％程度のプロピレンを含有する。なお、ベンゼン低減化装置にはＺＳＭ−５触媒が使用され、流動床式反応塔とスリップストリーム型再生装置が組合されている。導入される希釈ベンゼンの半分がアルキル化され、高オクタン価のアルキルベンゼンが生成される。希釈ベンゼンのアルキル化はエチレンの利用に好適であり、Ｃ₅ 〜Ｃ₇ オレフィンが共存しても問題はない。ベンゼンのアルキル化により、ベンゼンの減少に対してオクタン価の増加が認められる。
次に方法IIでは、ベンゼン前駆体である環状Ｃ₆ 化合物が接触改質装置へ供給されると、シクロヘキサンやメチルシクロペンタンからベンゼンが合成される。従って、ナフサスプリッターを事前に配置して、ベンゼン前駆体をサイドカットする必要がある。この方法IIでは、サイドカットした環状Ｃ₆ 化合物が接触改質装置をバイパスし、ベンゼン低減化装置へ導入される。大部分の環状Ｃ₆ 留分が改質用原料から除かれるため、低オクタン価のライトリフォーメートが若干少なくなり、Ｃ₅ ⁺ リフォーメートベンゼンが約１０容量％まで増加する。ライトリフォーメートもまたストリッパーで分離されベンゼン低減化装置へ導入される。この方法では接触改質装置から生成する水素量が少なくなるが、この減少量はベンゼンを飽和化するプロセスで使用される水素量より少ない。環状Ｃ₆ 留分をバイパスさせることにより、リフォーメートベンゼンは１／２から３／４少なくなり、残留ベンゼンはベンゼン低減化装置でＦＣＣオレフィンガスによりアルキル化される。同時にベンゼン低減化装置は極端に低オクタン価のＣ₆ ⁺ 直鎖パラフィンを分解し、環状Ｃ₆ 留分やリフォーメートベンゼンとともに留出される。直鎖Ｃ₆ 留分はプロパン，ブタンおよびライトオレフィンに分解される。生成したライトオレフィンの大部分はガソリンに転化される。ＦＣＣオフガスのエチレンおよびプロピレンのエチルベンゼンやクメンへの転化率は高く、ベンゼンのアルキル化およびＣ₆ ⁺ パラフィンの分解により、リサーチおよびモーターオクタン価が大きく増加する。この方法によれば、ＦＣＣオフガス燃料の過剰生成、あるいはＦＣＣガスプラントのプロピレン量の不足等の束縛条件を緩和することができるので、これを採用することにより、ＦＣＣの運転条件をより苛酷にすることが可能である。
さらに、これらの変法として、ベンゼンリッチ留分にライトオレフィン（例えばプロピレン）を混合通油して反応させるベンゼンのアルキル化プロセスを、既設固定床リフォーマーのセパレーターとスタビライザーの間に組み込むことによっても、ベンゼンの低減化を計ることができる。
【００１２】
また、ＦＣＣ（流動接解分解装置）ガソリン（ベンゼン0.９〜1.６容量％）、軽質ＦＣＣガソリン（ベンゼン１〜２容量％）及び脱硫重質ナフサ（ベンゼン0.９〜1.３容量％）は、通常経済性の点から脱ベンゼン処理せずに使用されるが、もちろん脱ベンゼン処理して使用してもよい。この場合、ＦＣＣガソリンのベンゼン量低減化は、例えば供給原料や運転条件を制御することによって行うことができ、また、軽質ＦＣＣガソリンのベンゼン量低減化は、ＦＣＣガソリンの分留時のカット温度の制御によって行うことができる。
また、脱硫重質ナフサのベンゼン量低減化は、ナフテン系原油の混合量を減らすことによって行うことができる。
【００１３】
次に、燃料油中の硫黄分を４０ｐｐｍ以下に抑えるためには、ガソリン基材の中で特に硫黄分の多い接触分解ガソリン中の硫黄分を低下させることが肝要である。そのためには、接触分解の原料油を水添処理によって脱硫して、接触分解装置に通油し、さらには生産された接触分解ガソリンをマーロックス装置などの脱硫装置に導入して脱硫を行うことが好ましい。
【００１４】
本発明の燃料油は、前記（１）〜（５）の条件を満たすとともに、通常、次の組成及び性状を有している。すなわち、通常ＭＴＢＥやメチルターシャリーアミルエーテル（ＭＴＡＥ），エチルターシャリーブチルエーテル（ＥＴＢＥ），エチルターシャリーアミルエーテル（ＥＴＡＥ）などの含酸素化合物含有量が０〜１５容量％、好ましくは２〜１５容量％、より好ましくは４〜１０容量％、芳香族分含有量が１５〜４５容量％、好ましくは２１〜３９容量％であって、炭素数９以上の芳香族分含有量が１０容量％以下、好ましくは８容量％以下、オレフィン分含有量２〜２５容量％、好ましくは５〜１９容量％で、また、〔リサーチ法オクタン価（ＲＯＮ）＋モーター法オクタン価（ＭＯＮ）〕／２の値が９３以上、好ましくは９４以上で、かつリード蒸気圧が0.４〜0.８ｋｇ／ｃｍ² である。
【００１５】
上記含酸素化合物は、オクタン価を向上させる作用を有し、その含有量が１５容量％を超えると、エンジン排ガス中のＮＯ_X が増加する傾向がみられる。また、芳香族分含有量が１５容量％未満では、得られる燃料油のオクタン価が充分に向上せず、オクタン価を向上させるために該含酸素化合物を多量に加えた場合、上述したように排気ガス中のＮＯ_X が増加するなど好ましくない事態を生じる。逆に４５容量％を超えると燃料系統に使用されている各種機器のゴムが劣化したり、排気ガス中の有害成分が増加する傾向がみられる。さらに、この芳香族分のうち、炭素数９以上の芳香族分含有量が１０容量％を超えると、中間気温（１５〜２５℃）での運転性、特に加速応答性が低下する傾向がみられる。なお、芳香族分含有量はＪＩＳ Ｋ−２５３６に準じて測定した値であり、また、炭素数９以上の芳香族分含有量は、ガスクロマトグラフによるガソリンの全組成分析（石油学会法ＪＰＩ−５Ｓ−９０に準拠）から算出した値である。
【００１６】
次に、オレフィン分含有量が上記範囲を逸脱すると、燃料油の安定性の面で問題が生じる。なお、ここでオレフィン分は、通常炭素数４〜１１のオレフィンを主成分とするものである。また、このオレフィン分含有量はＪＩＳ Ｋ−２５３６に準じて測定した値である。
（ＲＯＮ＋ＭＯＮ）／２の値が９３未満では、高走耐ノック性が不充分となるおそれがある。
また、燃料油中における炭素数９以上の芳香族分を１０容量％以下に抑制するためには、各ガソリン基材について、ガスクロマトグラフで全組成分析を行い、炭素数９以上の芳香族分が１０容量％以下になるようにすればよい。この際、当然に炭素数９以上の芳香族分以外の成分組成や性状（例えば、ＲＯＮ，蒸留性状，芳香族分及びオレフィン分など）についても、適正な範囲に入るように、上記全組成分析から判断すべきである。ここで、炭素数９以上の芳香族分を１０容量％以下になるように調節するための具体的方法は、様々に考えられるが、下記の（ａ）〜（ｅ）の方法を好適なものとして挙げることができる。
【００１７】
（ａ）接触改質ガソリン中の炭素数９以上の芳香族分の含有量を下げること。このためには、(i) 原料重質ナフサから重質分を除いて軽質化する、(ii)改質ガソリンから重質分を除去する、(iii) 接触改質装置の運転条件を調整するなどの手法がある。
（ｂ）燃料油を調製するにあたって、接触改質ガソリンの混合割合を下げること。
（ｃ）接触分解ガソリンから重質分を除いて軽質化すること。
（ｄ）改質ガソリンから石油化学原料としてのＢＴＸ（ベンゼン，トルエン，キシレン）を抜き取った後の炭素数９以上の芳香族分を使用しないこと。
（ｅ）改質ガソリンの代わりにトルエンを使用すること。
【００１８】
本発明の燃料油には、さらに必要に応じて、各種の添加剤を適宜配合することができる。
このような添加剤としては、例えばフェノール系やアミン系などの酸化防止剤、シッフ型化合物やチオアミド型化合物などの金属不活性剤、有機リン系化合物などの表面着火防止剤、コハク酸イミド，ポリアルキルアミン，ポリエーテルアミンなどの清浄分散剤、多価アルコール及びエーテルなどの氷結防止剤、有機酸のアルカリ金属やアルカリ土類金属塩，高級アルコールの硫酸エステルなどの助燃剤、アニオン性界面活性剤，カチオン性界面活性剤，両性界面活性剤などの帯電防止剤、アルケニルこはく酸のエステルなどの錆止め剤、キリザニン，クマリンなどの識別剤、天然精油，合成香料などの着臭剤、アゾ染料などの着色剤など、公知の燃料油添加剤が挙げられ、これらを一種あるいは二種以上添加することができる。また、これらの添加剤の添加量は状況に応じて適宜選定すればよいが、通常は添加剤の合計量として燃料油の0.１重量％以下とすることが望ましい。また、２サイクルエンジン用として、通常実施されている方法により、エンジンオイルを混合して利用することも可能である。
【００１９】
【実施例】
更に、本発明を実施例により詳しく説明するが、本発明はこれらの例によってなんら制限されるものではない。
なお、燃料油の性状及び性能は次の方法に従って求めた。
〔燃料油の性状〕
（１）オクタン価
ＪＩＳ Ｋ−２２８０に準拠して測定する。
（２）硫黄分
ＪＩＳ Ｋ−２５４１に従った微量電量滴定酸化法により測定する。
（３）蒸留性状（１）
ＪＩＳ Ｋ−２２５４に準拠して求める。
（４）全組成ガスクロマトグラフ法
石油学会法ＪＰＩ−５Ｓ−９０に準拠して、燃料油中の各炭化水素含有量を求める。値は重量％に近いので、各炭化水素密度から容量％に換算する。この分析法による各成分は沸点順に出てくる。
（イ）蒸留性状（２）
沸点２５℃未満に相当する各成分の量（容量％）を積算して算出する。同様にして、各温度範囲に相当する各成分の量を積算して算出し、蒸留性状（２）を求める。
（ロ）各留分のＲＯＮ
沸点２５℃未満に相当する各成分のＲＯＮと量（容量％）との積を積算し、これを積算量（容量％）で除して、沸点２５℃未満の留分のＲＯＮを求める。同様にして、各温度範囲の留分のＲＯＮを求める。
なお、一般に混合物のＲＯＮは、単純積算ＲＯＮよりも高い値を示す。この差はブレンドボーナス（又はオクタン価ボーナス）と呼ぶが、ここではそれを無視した。
（ハ）ベンゼン，トルエン，エチルベンゼン，キシレン，炭素数９以上の芳香族分含有量
該ガスクロ分析値を用いる。
（５）組成
ＪＩＳ Ｋ−２５３６に準じて測定する。
【００２０】
〔燃料油の性能〕
（１）中間気温での運転性
ＥＦＩ仕様の自動車用エンジンを用い、室温（２０℃）にて、エンジン回転数７００ｒｐｍから加速し、２５００ｒｐｍに到達するまでの時間（秒）で評価した。この時間が短いほど燃料の加速応答性が良好である。なお、ここでは実施例１の結果を基準にして、到達時間を％で表示した。
（２）排気ガス中のベンゼン濃度
ＴＲＩＡＳ２３−１９９１の「ガソリン自動車アイドリング、１１モード排出ガス試験法」に従い、かつＳＡＥ Ｐａｐｅｒ ９２０３２０に記載の方法に準拠して排ガス中のベンゼンを分析した。
【００２１】
実施例１及び比較例１〜４
第１表に示す性状のガソリン基材とＭＴＢＥを、第２表に示す割合で混合して、燃料油を調製し、その性状及び性能を求めた。その結果を第２表に示す。
【００２２】
【表１】

【００２３】
【表２】

【００２４】
【表１】

【００２５】
【表４】

【００２６】
【発明の効果】
本発明のガソリンエンジン用燃料油は、高速耐ノック性，加速性，燃焼性，始動性，運転性などの自動車の運転性能に優れるとともに、排気ガス中のベンゼン分や、ＮＯ_X 、ＳＯ_X などの少ない低公害性で、かつ無鉛高オクタン価のガソリンである。[0001]
[Industrial application fields]
The present invention relates to a novel fuel oil for gasoline engines. More specifically, the present invention relates to a fuel oil for a lead-free high-octane gasoline engine that has excellent driving performance of an automobile and low pollution.
[0002]
[Prior art]
Since the addition of lead compounds such as tetraethyl lead as an octane number improver has been regulated, unleaded high octane gasoline has been actively developed, and various unleaded high octane gasolines have been proposed and marketed. Furthermore, recently, unleaded high-octane gasoline to which oxygen-containing compounds such as alcohols and ethers are added has been proposed as a high-octane base.
As such a high octane gasoline, for example, gasoline obtained by adding methyl tertiary butyl ether (MTBE) to catalytically reformed gasoline and catalytically cracked gasoline, or to those blended with alkylate (JP-A-3-93894). No.), gasoline obtained by blending MTBE with a gasoline base material having a specific distillation property and component composition (Japanese Patent Laid-Open No. 3-263493), butane-butene fraction, aliphatic hydrocarbon component and aromatic carbonization A fuel oil composition (JP-A-3-229796) having a research octane number of 105 or more obtained by adding MTBE to a base oil in which a hydrogen component is blended at a certain ratio is known.
However, increasing the amount of MTBE added to increase the octane number of gasoline will result in lower fuel consumption due to density reduction and NO in exhaust gas._xWill increase. In addition, catalytic cracked gasoline, which is one of the main base materials of gasoline, has a higher sulfur content than other base materials, and this is the result of SO_xBring about an increase. Also, if the gasoline contains a large amount of sulfur, the catalyst's poisoning will reduce the activity of the three-way catalyst, resulting in NO in the exhaust gas._xWill increase.
Thus, the lead-free high-octane gasoline blended with MTBE that has been proposed so far aims to improve the octane number and operability, and NO in exhaust gas._xOr SO_xThe reduction in the amount of water was insufficient, and it was not always satisfactory from the viewpoint of pollution prevention.
In addition, when gasoline contains a large amount of benzene, the gasoline itself adversely affects the human body, and the exhaust gas contains a large amount of benzene, resulting in environmental pollution.
[0003]
[Problems to be solved by the invention]
Under such circumstances, the present invention is excellent in driving performance of automobiles such as high-speed knock resistance, acceleration, combustion, startability, drivability, benzene content in exhaust gas, NO_X, SO_XThe purpose of the present invention is to provide a fuel oil for gasoline engines with low pollution and low lead and high octane number.
[0004]
[Means for Solving the Problems]
  As a result of intensive research to develop a fuel oil for a lead-free high-octane gasoline engine that has excellent driving performance and low pollution, the present inventors have a specific distillation property and the research method octane number of each fraction. Is a gasoline engine fuel oil having an exhaust gas index, a benzene content, and a sulfur content of not more than specific values, and having a research octane number in the range of 97 to 102. And found that it can be adapted to the purpose. The present invention has been completed based on such findings.
  That is, the present invention provides (1)3 to 10% by volume of a fraction having a boiling point of less than 25 ° C.,The fraction having a boiling point of 25 ° C. or more and less than 75 ° C. is 35 to 50% by volume, and the fraction having a boiling point of 75 ° C. or more and less than 125 ° C. is 25 to 40% by volume.,The fraction having a boiling point of 125 ° C. or higher and lower than 175 ° C. is 10 to 30% by volume.And the fraction whose boiling point is 175 ° C or higher is 5% by volume or less.(2) The research method octane number of each fraction is 80 or more, (3) Formula (I)
Y = 1.07BZ + 0.12TO + 0.11EB + 0.05XY + 0.03C9 + A
       +0.005 [100- (BZ + TO + EB + XY + C9 + A)]
                                                            ... (I)
[In the formula, BZ is benzene content, TO is toluene content, EB is ethylbenzene content, XY is xylene content, C9 + A is aromatic content with 9 or more carbon atoms (both in fuel oil) % By volume). ]
The exhaust gas index Y represented by the formula is 5 or less, (4) the benzene content is 1% by volume or less, and the sulfur content is 40 ppm or less.And 2-10% by volume of oxygen-containing compoundsAnd (5) a fuel oil for gasoline engines, characterized in that the research octane number is 97 to 102.
[0005]
  The fuel oil of the present invention has (1) distillation properties,3 to 10% by volume of a fraction having a boiling point of less than 25 ° C.The fraction having a boiling point of 25 ° C. or more and less than 75 ° C. is 35 to 50% by volume, the fraction having a boiling point of 75 ° C. or more and less than 125 ° C. is 25 to 40% by volume, and the fraction having a boiling point of 125 ° C. or more and less than 175 ° C. is 10 to 30% by volume.And the fraction whose boiling point is 175 ° C or higher is 5% by volume or less.It is.
  When the fraction having a boiling point of less than 25 ° C. is less than 3% by volume, the startability is inferior, and when it exceeds 10% by volume, vapor lock or the like occurs. Also,If the fraction having a boiling point of 25 ° C. or more and less than 75 ° C., the fraction having a boiling point of 75 ° C. or more and less than 125 ° C., and a fraction having a boiling point of 125 ° C. or more and less than 175 ° C. are within the above ranges, the drivability and acceleration are excellent. It will be a thing. If any one of the values deviates from the above range, the drivability is lowered or the acceleration is lowered.Further, if the fraction having a boiling point of 175 ° C. or higher exceeds 5% by volume, the engine becomes dirty or the problem of oil dilution occurs.
[0006]
In the fuel oil of the present invention, (2) the research octane number (sometimes abbreviated as RON) of each fraction is 80 or more, preferably 85 or more. If this value is less than 80, a well-balanced anti-knock property cannot be obtained.
The distillation properties were determined by gas chromatography as described later, and the RON of each fraction was determined from the results of this gas chromatography method as described later.
Furthermore, (3) Formula (I)

[In the formula, BZ is benzene content, TO is toluene content, EB is ethylbenzene content, XY is xylene content, C₉ ⁺A represents the aromatic content of 9 or more carbon atoms (both are content in fuel oil and volume%). ]
The exhaust gas index Y expressed by is 5 or less, preferably 4 or less, more preferably 3.5 or less. The index Y indicates the ratio of benzene contained in the exhaust hydrocarbon produced when the fuel oil is burned in the engine, and each coefficient is the benzene content (wt%) in the exhaust hydrocarbon / fuel oil. It is a value of content (volume%) of each component in the inside. That is, this value is the largest for benzene, and then decreases as the number of substituents on the benzene ring increases, such as monoalkylbenzene, dialkylbenzene, and trialkylbenzene. Paraffin and olefin are extremely small, 0.005, respectively. [100- (BZ + TO + EB + XY + C₉ ⁺A)] represents components other than the aromatic component in the fuel oil. When the exhaust gas index Y represented by the above formula (I) exceeds 5, the exhaust gas cannot be sufficiently reduced in pollution. In addition, content of each aromatic content is the value computed from the total composition analysis (based on Petroleum Institute method JPI-5S-90) by the gas chromatograph method.
[0007]
In the fuel oil of the present invention, (4) the benzene content is 1.0 vol%, preferably 0.5 vol% or less, and the sulfur content is 40 ppm or less, preferably 30 ppm or less. If the benzene content exceeds 1.0% by volume, the fuel oil itself may adversely affect the human body, or the benzene content in the exhaust gas may increase, causing environmental pollution. If the sulfur content exceeds 40 ppm, SO in the exhaust gas_XAnd the poisoning of the catalyst reduces the activity of the three-way catalyst, resulting in NO in the exhaust gas._XWill also increase. The sulfur content is a value measured by a microcoulometric titration method according to JIS K-2541.
Furthermore, in the fuel oil of the present invention, (5) the research octane number is in the range of 97 to 102, preferably 98 to 101.
[0008]
The fuel oil of the present invention is not particularly limited as long as it satisfies the above conditions (1) to (5), and the origin thereof is not particularly limited. For example, the following (1) ) To (5) can be prepared by appropriately blending so as to satisfy the conditions. Examples of the gasoline base material include light naphtha obtained by fractionating a naphtha fraction obtained by atmospheric distillation of crude oil, cracked gasoline obtained by catalytic cracking or hydrocracking, catalytic reforming, and the like. The remaining fraction obtained by removing the benzene fraction from the reformed gasoline by the method described later, polymerized gasoline obtained by olefin polymerization, alkylate obtained by adding (alkylating) a lower olefin to a hydrocarbon such as isobutane, Examples include isomerates obtained by isomerization of straight-chain lower paraffin hydrocarbons, de-n-paraffin oils, fractions of these specific ranges, and aromatic hydrocarbons.
[0009]
Examples of the method for reducing the amount of benzene in the reformed gasoline (benzene 4 to 10% by volume) include, for example, (1) changing the operating conditions of the catalytic reformer, and (2) C in the desulfurized heavy naphtha of the raw material.₆Removal method by distillation of the fraction, (3) Method of removing the benzene fraction from the reformed gasoline by distillation, (4) By catalytic reaction, the benzene content in the reformed gasoline is hydrotreated and converted to cyclohexane, Further, this is introduced into an isomerizer to isomerize it into a high octane isomer, and (5) a method of alkylating the benzene content in the reformed gasoline and converting it to a high octane alkyl aromatic content by catalytic reaction. And (6) The benzene content removed and separated by the above method (2) is alkylated with FCC (fluidized catalytic cracking unit) off-gas containing a large amount of ethylene and the like to convert it into a high octane-valent alkyl aromatic content. There are methods.
The above method (1) is a method of lowering the reaction temperature, but the C in the raw material desulfurized heavy naphtha.₆The dehydrogenation reaction of naphthene is rate limiting, and it is difficult to reduce the benzene content in the reformed gasoline to 4% by volume or less. In the method (2), the light fraction in the raw desulfurized heavy naphtha is used. Minute (C₆However, the limit of the benzene content in reformed gasoline is about 1.5% by volume. This is because benzene is produced from hydrocarbons having 7 or more carbon atoms. Therefore, the method (3) is suitable as a method for reducing the amount of benzene in the reformed gasoline. This method is usually a method of removing the benzene fraction from the reformed gasoline using the first splitter and the second splitter, and the benzene content in the obtained debenzene reformed gasoline is about 0 to 0.5% by volume. Drop to. Further, the benzene content can be refined and used for petrochemical raw materials such as benzene products and raw materials such as cyclohexane and styrene monomers. Furthermore, if this benzene is alkylated, it can be converted to alkylbenzene such as toluene and xylene. Further, if cyclohexane is isomerized, it can be converted to methylcyclopentane.
In the methods (4) and (5), it is necessary to install a new treatment apparatus for the catalytic reaction. However, when there is no method for utilizing the extracted benzene content, and a new fraction obtained from the apparatus. However, when it can be used as a gasoline production base or petrochemical raw material, it can be a more efficient benzene reduction method than the method (3).
In addition, there are hydrotreatment method of benzene fraction and benzene extraction method. Here, in the hydrotreating method of a benzene fraction, first, a fraction containing a benzene precursor is separated by distillation, the remaining fraction is subjected to a catalytic reformer, and the resulting reformate is introduced into a splitter and introduced into a splitter. And is saturated with hydrogen. Furthermore, the three components are blended again to make a mixed reformate. On the other hand, in the benzene extraction method, hydrodesulfurized naphtha is distilled and i-C_Five~ N-C₆The fraction is separated and 70 ° C⁺Apply the fraction to the catalytic reformer and use a splitter to_FiveSeparated into a fraction, a benzene toluene fraction (BT fraction) and a reformate fraction. Of these, the BT fraction is introduced into an extractor and separated into benzene (B), toluene (T) and raffinate. Benzene is used as a petrochemical raw material, and the reformate high-boiling fraction is C as it is._FiveMix with fraction, toluene and raffinate to make mixed reformate.
[0010]
Next, the method (4) will be described in more detail. In this method, reformed gasoline (reformate) is distilled and C_Five, C₆After cutting the light reformate fraction containing the fraction, this is hydrotreated to convert the benzene in the fraction to cyclohexane, and this cyclohexane is further introduced into the isomerization apparatus, so that methylcyclopentane and n- As the ring opens to hexane, n-hexane is further converted to a higher octane isomer. This method can be broadly divided into two processes in which these reactions are carried out in a two-column system or a single-column system.
Among these, the outline of the two-column process is as follows. First, after the raw material oil and hydrogen are preheated by a heat exchanger, the temperature is raised in a heating furnace and introduced into a hydrogenation reaction tower (first reaction tower). Since the hydrogenation reaction tower is an exothermic reaction, the catalyst layer is cooled by hydrogen gas, and the reaction temperature is controlled. Since hydrogenolysis is suppressed by suppressing the temperature rise, the liquid yield can be increased. The treated oil exiting from the hydrogenation reaction tower is introduced into an isomerization reaction tower (second reaction tower) packed with a zeolite-based isomerization catalyst. Since the second reaction column is operated at substantially the same temperature as the first reaction column, no heat exchanger is required. The reaction product leaving the isomerization reaction tower is sent to the separation tower for gas-liquid separation. Hydrogen is recycled to the reaction tower, the liquid phase is sent to the stabilizer, and the off-gas is separated.
Next, in the one-column process, since the hydrogenation reaction and the isomerization reaction are carried out in the same reaction column, the temperature control is performed with great care. Cooled hydrogen is supplied to each stage of the reaction tower. The downstream portion has almost the same configuration as the above-described two-column process. In either method, the reaction conditions (temperature, pressure) applied to the normal isomerization reaction are performed under mild conditions, and both use hydrogen generated in catalytic reforming.
In the above method (4), the hydrogenation reaction catalyst used therefor is a platinum / alumina system, regardless of whether it is a two-column or single-column process, and is highly active and stable. The yield is high. The isomerization reaction catalyst is a zeolite-based catalyst and is passed through oil at almost the same temperature as the hydrogenation reaction. Therefore, the heat exchange and cooling system are simplified, the construction cost is low, and it is economical. In addition, it is possible to extend the life of the catalyst under mild operating conditions. As an example of these operating conditions, the hydrogenation reaction is performed at a pressure of 29.6 atm (absolute pressure), an inlet temperature of 180 to 250 ° C., and a liquid hourly space velocity (LHSV) of 4 to 6 hours.^-1The isomerization reaction is performed at a pressure of 29.6 atm (absolute pressure), an inlet temperature of 240 to 270 ° C., a liquid hourly space velocity (LHSV) of 1 to 3 hours.^-1Can be done.
If the benzene content is simply reduced, the benzene concentration is 30% by volume or less._Five~ C₆By hydrotreating the fraction using various noble metal catalysts, it can be efficiently converted to cyclohexane and side reactions can be suppressed as much as possible.
[0011]
Next, the method (6) will be described in more detail. This method is roughly divided into the following two methods, Method I and Method II.
First, in Method I, first, C_FiveThe above reformate fraction is distilled to C_FiveFraction, fraction containing benzene and C₇ ⁺Separate into three fractions of heavy reformate. The FCC off gas is washed with an amine to remove hydrogen sulfide, and then immediately introduced into a benzene reduction device (for example, MBR device manufactured by Mobil Corporation). The FCC offgas is mostly ethylene but contains about 5-10% propylene. Note that a ZSM-5 catalyst is used for the benzene reduction apparatus, and a fluidized bed type reaction tower and a slip stream type regenerator are combined. Half of the diluted benzene introduced is alkylated to produce a high octane alkylbenzene. Alkylation of dilute benzene is suitable for ethylene utilization and C_Five~ C₇There is no problem even if olefin coexists. Due to the alkylation of benzene, an increase in octane number is observed with respect to the decrease in benzene.
Next, in Method II, cyclic C which is a benzene precursor₆When the compound is supplied to the catalytic reformer, benzene is synthesized from cyclohexane or methylcyclopentane. Therefore, it is necessary to place a naphtha splitter in advance and side-cut the benzene precursor. In this method II, side-cut annular C₆The compound bypasses the catalytic reformer and is introduced into the benzene reduction unit. Most annular C₆Since the distillate is removed from the reforming raw material, the low octane number light reformate is slightly reduced._Five ⁺Reformate benzene is increased to about 10% by volume. The light reformate is also separated by a stripper and introduced into a benzene reduction apparatus. This method reduces the amount of hydrogen produced from the catalytic reformer, but this reduction is less than the amount of hydrogen used in the process of saturating benzene. Ring C₆By bypassing the fraction, reformate benzene is reduced from 1/2 to 3/4, and residual benzene is alkylated with FCC olefin gas in a benzene reduction unit. At the same time, the benzene reduction device uses an extremely low octane C₆ ⁺Decompose linear paraffin to form cyclic C₆Distilled with distillate and reformate benzene. Linear C₆The fraction is broken down into propane, butane and light olefins. Most of the light olefin produced is converted to gasoline. FCC off-gas ethylene and propylene conversion to ethylbenzene and cumene is high, benzene alkylation and C₆ ⁺Degradation of paraffin greatly increases research and motor octane numbers. According to this method, it is possible to relax constraints such as excessive generation of FCC off-gas fuel or insufficient propylene content in the FCC gas plant. By adopting this, the operating conditions of the FCC are made more severe. It is possible.
Furthermore, as a modification of these, a benzene alkylation process in which a light olefin (for example, propylene) is mixed and reacted with a benzene-rich fraction is reacted between a separator and a stabilizer of an existing fixed bed reformer. Benzene can be reduced.
[0012]
Also, FCC (fluidized cracking cracker) gasoline (benzene 0.9-1.6% by volume), light FCC gasoline (benzene 1-2% by volume) and desulfurized heavy naphtha (benzene 0.9-1.3% by volume). %) Is usually used without debenzene treatment from the viewpoint of economy, but of course, it may be used after debenzene treatment. In this case, the amount of benzene in FCC gasoline can be reduced by, for example, controlling the feedstock and operating conditions, and the amount of benzene in light FCC gasoline can be reduced by reducing the cut temperature during FCC gasoline fractionation. Can be done by control.
In addition, the benzene content of desulfurized heavy naphtha can be reduced by reducing the amount of naphthenic crude oil mixed.
[0013]
Next, in order to suppress the sulfur content in the fuel oil to 40 ppm or less, it is important to reduce the sulfur content in the catalytic cracked gasoline having a particularly high sulfur content in the gasoline base material. For this purpose, the catalytic cracking feedstock is desulfurized by hydrogenation treatment, passed through a catalytic cracking device, and the produced catalytic cracked gasoline is introduced into a desulfurization device such as a Marrox device for desulfurization. preferable.
[0014]
The fuel oil of the present invention satisfies the above conditions (1) to (5) and usually has the following composition and properties. That is, the content of oxygenated compounds such as MTBE, methyl tertiary amyl ether (MTAE), ethyl tertiary butyl ether (ETBE), ethyl tertiary amyl ether (ETAE) is usually 0 to 15% by volume, preferably 2 to 15% by volume. %, More preferably 4 to 10% by volume, and the aromatic content is 15 to 45% by volume, preferably 21 to 39% by volume, and the aromatic content having 9 or more carbon atoms is 10% by volume or less, Preferably, it is 8 volume% or less, the olefin content is 2 to 25 volume%, preferably 5 to 19 volume%, and the value of [Research Octane Number (RON) + Motor Method Octane Number (MON)] / 2 is 93 or more. , Preferably 94 or more, and the reed vapor pressure is 0.4 to 0.8 kg / cm.²It is.
[0015]
The oxygen-containing compound has an effect of improving the octane number, and when its content exceeds 15% by volume, NO in the engine exhaust gas_XThere is a tendency to increase. Further, when the aromatic content is less than 15% by volume, the octane number of the obtained fuel oil is not sufficiently improved, and when the oxygen-containing compound is added in a large amount in order to improve the octane number, the exhaust gas as described above. NO inside_XAn unfavorable situation occurs, such as an increase. Conversely, if it exceeds 45% by volume, the rubber of various devices used in the fuel system tends to deteriorate or harmful components in the exhaust gas tend to increase. Furthermore, when the content of aromatics having 9 or more carbon atoms in this aromatic content exceeds 10% by volume, the operability at an intermediate temperature (15 to 25 ° C.), particularly the acceleration responsiveness tends to decrease. It is done. The aromatic content is a value measured according to JIS K-2536, and the aromatic content with 9 or more carbon atoms is analyzed by gas chromatograph total composition analysis of gasoline (Japan Petroleum Institute method JPI-5S). -Based on -90).
[0016]
Next, if the olefin content exceeds the above range, a problem arises in terms of the stability of the fuel oil. In addition, an olefin content here has a C4-C11 olefin as a main component normally. The olefin content is a value measured according to JIS K-2536.
If the value of (RON + MON) / 2 is less than 93, the high running knock resistance may be insufficient.
In addition, in order to suppress the aromatic content of 9 or more carbon atoms in fuel oil to 10% by volume or less, each gasoline base material is analyzed by gas chromatograph, and the aromatic content of 9 or more carbon atoms is determined. What is necessary is just to make it become 10 volume% or less. In this case, naturally, the above total composition analysis is performed so that the component composition and properties other than the aromatic component having 9 or more carbon atoms (for example, RON, distillation property, aromatic component, olefin component, etc.) are also in an appropriate range. Should be judged from Here, various specific methods for adjusting the aromatic content of 9 or more carbon atoms to 10% by volume or less can be considered, but the following methods (a) to (e) are preferable. Can be mentioned.
[0017]
(A) Decreasing the content of aromatics having 9 or more carbon atoms in catalytically modified gasoline. To this end, (i) remove heavy components from raw material heavy naphtha and lighten (ii) remove heavy components from reformed gasoline, (iii) adjust the operating conditions of the catalytic reformer There are methods such as.
(B) In preparing the fuel oil, the mixing ratio of the catalytic reforming gasoline is lowered.
(C) Lightening by removing heavy components from catalytic cracked gasoline.
(D) Do not use aromatics having 9 or more carbon atoms after extracting BTX (benzene, toluene, xylene) as petrochemical raw material from reformed gasoline.
(E) Use toluene instead of reformed gasoline.
[0018]
Various additives can be appropriately blended in the fuel oil of the present invention as necessary.
Examples of such additives include phenolic and amine antioxidants, metal deactivators such as Schiff compounds and thioamide compounds, surface ignition inhibitors such as organophosphorus compounds, succinimides, poly Detergents such as alkylamines and polyetheramines, anti-icing agents such as polyhydric alcohols and ethers, organic acid alkali metal and alkaline earth metal salts, auxiliary alcohols such as higher alcohol sulfates, anionic surfactants Antistatic agents such as cationic surfactants and amphoteric surfactants, rust inhibitors such as esters of alkenyl succinic acid, identification agents such as kilyzanine and coumarin, odorants such as natural essential oils and synthetic fragrances, azo dyes, etc. Known fuel oil additives such as colorants can be mentioned, and one or more of these can be added. The addition amount of these additives may be appropriately selected according to the situation, but it is usually desirable that the total amount of the additive is 0.1% by weight or less of the fuel oil. Moreover, it is also possible to mix and use engine oil for a two-cycle engine by a commonly practiced method.
[0019]
【Example】
Furthermore, although an Example demonstrates this invention in detail, this invention is not restrict | limited at all by these examples.
The properties and performance of the fuel oil were determined according to the following method.
[Properties of fuel oil]
(1) Octane number
Measured according to JIS K-2280.
(2) Sulfur content
It is measured by a microcoulometric titration method according to JIS K-2541.
(3) Distillation properties (1)
Obtained in accordance with JIS K-2254.
(4) Total composition gas chromatographic method
Each hydrocarbon content in fuel oil is calculated | required based on Petroleum Institute method JPI-5S-90. Since the value is close to% by weight, it is converted from each hydrocarbon density to volume%. Each component by this analysis method comes out in order of boiling point.
(I) Distillation properties (2)
The amount (volume%) of each component corresponding to a boiling point of less than 25 ° C. is integrated and calculated. Similarly, the amount of each component corresponding to each temperature range is integrated and calculated to obtain the distillation property (2).
(B) RON of each fraction
The product of RON and the amount (volume%) of each component corresponding to a boiling point of less than 25 ° C. is integrated, and this is divided by the integrated amount (volume%) to obtain the fraction RON having a boiling point of less than 25 ° C. Similarly, the RON of the fraction in each temperature range is obtained.
In general, the RON of the mixture is higher than the simple integration RON. This difference is called a blend bonus (or octane bonus), but was ignored here.
(C) Benzene, toluene, ethylbenzene, xylene, aromatic content with 9 or more carbon atoms
The gas chromatographic analysis value is used.
(5) Composition
Measured according to JIS K-2536.
[0020]
[Performance of fuel oil]
(1) Drivability at intermediate temperature
Using an EFI specification automobile engine, the engine was accelerated from 700 rpm at room temperature (20 ° C.) and evaluated in terms of time (seconds) until reaching 2500 rpm. The shorter this time, the better the acceleration response of the fuel. Here, the arrival time is expressed in% based on the result of Example 1.
(2) Benzene concentration in exhaust gas
Benzene in exhaust gas was analyzed in accordance with TRIAS 23-1991 “Gasoline automobile idling, 11-mode exhaust gas test method” and in accordance with the method described in SAE Paper 920320.
[0021]
Example1And Comparative Examples 1-4
  A gasoline base material having the properties shown in Table 1 and MTBE were mixed at a ratio shown in Table 2 to prepare a fuel oil, and its properties and performance were determined. The results are shown in Table 2.
[0022]
[Table 1]

[0023]
[Table 2]

[0024]
[Table 1]

[0025]
[Table 4]

[0026]
【The invention's effect】
The fuel oil for gasoline engine of the present invention is excellent in driving performance of automobiles such as high-speed knock resistance, acceleration performance, combustion performance, startability, driving performance, etc., benzene content in exhaust gas, NO_X, SO_XIt is a low-pollution, low lead and high-octane gasoline.

Claims (7)

(1) The fraction having a boiling point of less than 25 ° C is 3 to 10% by volume, the fraction having a boiling point of 25 ° C to less than 75 ° C is 35 to 50% by volume, and the fraction having a boiling point of 75 ° C to less than 125 ° C is 25 to 40% by volume. The fraction having a boiling point of 125 ° C. or more and less than 175 ° C. is 10 to 30% by volume and the fraction having a boiling point of 175 ° C. or more is 5% by volume or less . (2) The research method octane number of each fraction is 80 or more. (3) Formula (I)
Y = 1.07BZ + 0.12TO + 0.11EB + 0.05XY + 0.03C 9 + A + 0.005 [100- (BZ + TO + EB + XY + C 9 + A) ]
... (I)
[In the formula, BZ is benzene content, TO is toluene content, EB is ethylbenzene content, XY is xylene content, C ₉ ⁺ A is aromatic content with 9 or more carbon atoms (both fuel oil The content is the volume%). ]
(4) The benzene content is 0.7% by volume or less, the sulfur content is 30 ppm or less, and the oxygen-containing compound is 2 to 10% by volume. And (5) A fuel oil for a gasoline engine having a research octane number of 97 to 102.   The fuel oil for gasoline engines according to claim 1, wherein the aromatic content is 15 to 45% by volume.   The fuel oil for gasoline engines according to claim 1 or 2, wherein the content of aromatics having 9 or more carbon atoms is 10% by volume or less.   The fuel oil for gasoline engines according to any one of claims 1 to 3, which has a research octane number of 98 to 101.   The fuel oil for gasoline engines according to any one of claims 1 to 4, wherein the olefin content is 2 to 25% by volume. The fuel oil for gasoline engines according to any one of claims 1 to 5, wherein the oxygen compound content is 2 to 5% by volume.   The fuel oil for gasoline engines according to any one of claims 1 to 6, wherein the benzene content is 0.5 vol% or less.