ENVIRO-COAT: ENVIROnmentally assisted, engineered Corrosion prOducts for Aqueous corrosion miTigation

对能源行业成功运营最直接的威胁之一是碳钢管道在运输高温(&gt；120oC)含水介质时的内部腐蚀。这种退化机制在核能、石油和天然气、碳捕获和储存以及地热等行业中都很明显。未能妥善管理内部管道退化会导致意外故障，不仅导致财务损失，而且重大泄漏还可能造成严重的环境后果。碳钢管道最常见的缓蚀方法是在工艺流体中添加缓蚀剂。然而，这类化学品的环境状况通常很差，那些符合欧洲关于毒性和生物累积特性的立法的化学品通常在高温下缺乏将腐蚀抑制到可接受水平所需的效率。在咪唑啉化学(工业上使用的最常见的分子之一)的背景下，抑制作用差的原因是它们倾向于水解成效率较低的前体。除了这些挑战之外，在设施的整个生命周期内使用缓蚀剂的成本可能特别高。2016年，欧洲每年用于缓蚀剂的支出超过20亿GB，其中发电和石油和天然气行业占据了这两个份额的最大比例。显然，如果碳钢要继续成为高温环境下最有利的材料，就需要在高温水环境下如何控制内部管道腐蚀方面进行阶段性改变。这项建议侧重于设计一种既经济又环保的抑制腐蚀的解决方案。该建议侧重于利用碳钢内壁暴露在高温含水介质中时自然形成的腐蚀产物的保护性能。高温下最常见的腐蚀产物是磁铁矿，它是一种具有独特磁性和电性的氧化铁。虽然磁铁矿已被证明对碳钢的均匀腐蚀提供了有效的屏障，但其导电性质允许这种氧化物支持电化学反应，从而通过电偶效应导致局部腐蚀发生。这项建议的目的是确定一种增强磁铁矿结构以抑制其电化学活性的方法，与传统的缓蚀剂相比，产生一层对一般和局部腐蚀都具有更好的保护。为了增强磁铁矿的层，将采用一种在过渡金属离子存在的情况下共沉淀的方法。这项工作的假设是，将微量的过渡金属离子掺入磁铁矿的晶格中(直接通过溶液提供或从腐蚀金属本身提供)将足以改变层的电化学活性。过渡金属改变磁铁矿的化学和物理性质的能力已经在其他学科中得到证明(例如，催化剂开发)。然而，这种方法从来没有在腐蚀管理的背景下被鼓励。通过选择适当的过渡金属，这些过渡金属在增加磁铁矿所需的浓度下表现出零或最小的毒性，可以开发出一种“批量”处理方法，或更好的合金化碳钢，从而消除了连续注入缓蚀剂的要求。这些方法将为部署传统的有机缓蚀剂提供更具成本效益、更高效和更环保的替代方案。

One of the most pertinent threats to successful operations in the energy sector is internal corrosion of carbon steel pipework when transporting high temperature (>120oC) aqueous media. This degradation mechanism is apparent in the nuclear, oil and gas, carbon capture and storage and geothermal industries to name a few. Failure to manage internal pipeline degradation properly results in unexpected failures, leading not only to financial losses, but significant leaks can also have severe environmental consequences. The most common method of corrosion mitigation for carbon steel pipelines is via the addition of corrosion inhibitors to process fluids. However, such chemicals typically have a poor environmental profile and those which conform to European legislation regarding toxicity and bioaccumulation characteristics typically lack the required efficiency at elevated temperatures to suppress corrosion to acceptable levels. In the context of imidazoline chemistries (one of the most common classes of molecules used in industry) the poor inhibition is attributed to their propensity to undergo hydrolysis into their less efficient pre-cursors. In addition to these challenges, the cost of corrosion inhibitors over the lifetime of a facility can be particularly high. In 2016, the annual expenditure on corrosion inhibitors in Europe was in excess of £2 billion, with power generation and oil and gas sectors occupying the two largest proportions of this share.It is apparent that a step change is required relating to how internal pipeline corrosion is controlled in high temperature aqueous environments if carbon steel is to continue as the most favourable material of choice in high temperature environments. This proposal focuses on engineering a solution to suppress corrosion which is cost effective and greener for the environment.The proposal focuses on harnessing the protective properties of corrosion products which naturally form on the internal walls of carbon steel when exposed to high temperature aqueous media. The most commonly observed corrosion product at elevated temperature is magnetite, an iron oxide which possesses unique magnetic and electrical properties. Although magnetite has been shown to provide an effective barrier to uniform corrosion of carbon steel, its electrically conductive nature allows this oxide to support electrochemical reactions which results in localised corrosion occurring through galvanic effects. The intention of this proposal is to identify a method of augmenting the magnetite structure to suppress its electrochemical activity, producing a layer which provides superior protection against both general and localised corrosion compared to conventional corrosion inhibitors.In order to augment the magnetite layer, a method of co-precipitation in the presence of transition metal ions will be adopted. The hypothesis for this work is that the incorporation of trace amounts of transition metal ions into the crystalline lattice of magnetite (supplied directly via the solution or from within the corroding metal itself) will be sufficient to alter the layers electrochemical activity. The ability of transition metal to modify the chemical and physical properties of magnetite has been demonstrated in other disciplines (e.g. catalyst development). However, such an approach has never been instigated in the context of corrosion management.By selection of appropriate transition metals which exhibit zero or minimal toxicity at the required concentrations for augmenting magnetite, a 'batch' method of treatment, or superior alloyed carbon steels can be developed, eliminating the requirement for continuous injection of corrosion inhibitors. These approaches will provide more cost effective, efficient and greener alternatives to the deployment of conventional organic corrosion inhibitors.