Group I or Group II Production – Is There a Choice?

一类油还是二类油，有一个选择吗？

近期我们看到有关欧盟和远东很多一类基础油产能关闭的公告。我们很想知道这一趋势何时停止。接下来的故事里有几点值得考虑：

首先，想挽救现有的炼厂，要看能否达到以下任意一点：一类油的应用带来实际的可观利润或在技术上是无可替代的？

回答这个问题，我们必须注意工艺油和稀释油确实需要一类芳烃基础油所提供的更多溶剂。

尽管环烷基基础油可以提供一部分溶剂（或基液），但它们可以填补的空白是有限的。全球环烷基产品每年只有350万吨，而一类油用量接近它的5倍。

美国海湾地区一类和二类油相似粘度级别的价格如果有差别也很小，的确只有一类光亮油获得一个明显的溢价。这表明仍有工厂坚持一类基础油的生产。不是必须以较大的折扣而促销。这与我们了解相符。换句话说，仍有大量的性能接近API SG/CF或是更低的曲轴油，还有船用油和一些工业油品，它们是一类油的大用户，不可能很快改变。

更适合于二类油的SAE40船用汽缸油的需求量尚有待起步，意味着对于SAE50粘度船用汽缸油所需的光亮油的需要仍将继续。

其次，如果确实需要，我们能否在一些更现代的生产二类油的工厂降格生产一类基础油呢？今天的一些二类工厂实际上是其它方向转换的结果。大体上，加氢工艺可以被用于一类油的生产。的确，至今，一些欧洲和远东的工厂仅在升级阶段使用这一方法。芳烃饱合阶段所需要的催化剂类型必将是无硫敏感的镍和钼类的。

如此这样的路径有什么优势可言？它可能去除一类油的溶剂精制工艺要求高品质原油的限制，这将降低炼厂的原料成本。这也是二类基础油已有的优势。这也将会在一定程度上改善一类产品的收益模式。因为将不再生产提余物（石蜡）。当然，它们中大部分都被转化成基础油的分子，就像二类或是三类油产品通常那样。

一类馏份使用催化脱蜡也是有可能的，尽管通常不适于光亮油。当然，较老式的石蜡裂解催化脱蜡已被用于一部分一类油。如果粗蜡中是充分硫化而且无氮的，贵金属可以被做为异构催化剂。

这会有一些什么缺点吗？当然，一类基础油将会接近无硫类似于二类油基础油，但是对于一类基础油中含有的芳烃成分就未必是好事，一些一类基础油中残余的硫扮演着保护基础油分子结构完整性的角色。它在基础油加入添加剂前还担当一种天然的辅助抗氧化剂，而且硫甚至可以促进加剂后成品润滑油的性能。然而二类和三类油根本上是无硫的，但他们不需同样的限制，因为二、三类油中残留的多环芳烃，作为主要的不稳定的因素，它的浓度很低，通常会在补充加氢精制中被去掉。

当一类油采取加氢处理时，带来更多原油适应性和潜在产能提升的好处，这些可能发生吗？只有市场说了算。相关技术是很成熟的，因此不太可能是技术上的推动力，仅仅是因为市场供应的推动。有趣的是，有报道称Repsol已经升级它在西班牙的一类基础油生产装置，远景规划是2017年开始生产加氢一类基础油。

再有，制造业经济能否有足够的提升以支持持续的一类油生产？当前，一类油生产中一大亮点是光亮油的副产品。假如炼厂可以为制造光亮油时产生的馏出物成分找到用户，如果收益可以保证的话，正在运行的光亮油工厂将会有不错的前景。的确，今天一些一类油基础油工厂包括专营光亮油的加入这一行列。

光亮油生产的主要问题是脱蜡的步骤，在当前以溶剂为基础的工艺形式中，一般的生产瓶颈是由于粘度派生时蜡过滤的极限。然而催化脱蜡可被用于设定光亮油的倾点，石蜡基原料的产品通常易出现外观上不透明，因为今天催化技术还不能处理重组分的石蜡尾油。正在为此寻找一种催化剂，将会打开很多新的业务机会。

归根到底，尽管光亮油生产是后续一类油生产的一大亮点，一类油的馏分油离过剩还很远，生产可以更划算。

We’ve seen recent announcements of more API Group I capacity closing in the European Union and the Far East. And we have to wonder where it will stop. Several points deserve consideration in this continuing storyline.

First, will there come a point at which there is actually a significant premium for Group I grades in applications or which Group I is a technical must-have, thereby saving the remaining plants?

In answering this question, it must be noted that some process oils and diluent oils really need the added solvency that Group I aromatics provide.

While naphthenic stocks can supply some of this solvency, there is a limit to how much of a gap they can fill.Global naphthenic production is only about 3.5 million tons per year and Group I is around five times that.

U.S. Gulf prices for comparable grades of Group I and Group II show little, if any, differential. Indeed only Group I bright stock commands an obvious premium. This indicates that there is still a home for remaining Group I production and that it does

not have to be heavily discounted to move. This fits with what we know; namely, that there is still a large volume of crankcase products, around API SG/CF performance levels and below, as well as marine and some industrial lubes, that are large onsumers

of Group I. That is unlikely to change any time soon.

The take-up of SAE 40 grade marine cylinder oils – more suited to Group II grade structures – has yet to take off, meaning there is a continuing need for bright stock-like viscosity grades to support SAE 50 cylinder oils.

Second, if we really wanted to, could we ever go back to making Group I base oils in some of the more modern plants set up for Group II? Some of today’s Group II plants

are in fact the result of conversions in the other direction. In principle, hydrotreating

technology can be applied to Group I production. Indeed, until recently, some plants in Europe and the Far East used just this approach in the upgrading stage. The types of catalysts needed for the aromatics saturation stage would certainly have to be nonsulfur-sensitive nickel and molybdenum types.

It is also possible to use catalytic dewaxing for Group I distillate grades, even if not routinely for bright stocks. Certainly, the older type of wax-cracking catalytic dewaxing has been used in the past for Group I, and if the waxy cuts were sufficiently sulfur- and

nitrogen-free, noble metal isomersation catalysts could be considered.

What would be the advantages, if any, of such an approach? It would remove some of the constraints of high crude specificity needed for solvent processing of Group I stocks, which puts a cost premium on the feedstock to refineries. This is an advantage Group II already has. It would also go some way toward improving the yield pattern of

Group I production because no extracts would be produced. Rather, they would largely be converted to base stock molecules, as is the case in Group II or Group III

production.

Would there be any drawbacks? Certainly, the Group I base oils produced would be almost as sulfurfree as Group II base stocks, and that is not necessarily good for the type of aromatics compositions and levels found in Group I stocks. Some residual sulfur in Group I plays a part in maintaining the molecular integrity of Group I stocks.

It also acts as a natural secondary antioxidant until the base stocks are additized, and sulfur can even boost finished lube performance after additization. While Group II and Group III are essentially sulfur-free, they do not suffer the same limitations because residual polyaromatics, the main culprits of instability, are low in concentration and normally hydrofinished away.

With the benefits of more crude flexibility and potential yield improvements when hydroprocessing Group I production, is it likely to happen? Only the market can dictate that. The technology is well established, so there is unlikely to be a technology push, only a market supply pull. Interestingly, Repsol is reported to have upgraded its

Group I production facilities in Spain with the prospect of making hydrogenated Group I by 2017.

Third, could manufacturing economics ever improve enough to underpin continued

Group I production? Currently, a big plus for continued Group I production is the associated production of bright stock. Provided refiners can find uses for the distillate fractions when making bright stocks, there is the prospect of running bright stock-only plants if premiums hold. Indeed, some Group I plants include dedicated bright stock trains today.

The issue with bright stock production is the dewaxing step, which, in its current solvent-based form, is always a production bottleneck due to viscosity derived wax filtration limits. While catalytic dewaxing can be used to set a pour point for bright stock, production from paraffinic feeds usually tends to look hazy because today’s catalyst technologies just cannot cope with the heavy wax ends. Finding a catalytic solution to this issue would open up many new business opportunities.

In the final analysis, while bright stock production is a big plus for continued Group I production, even the distillate grades of Group I are far from redundant and could be made more cost-effective if need