油田常用聚合物的清洁氧化降解研究

发布时间：2018-08-14 18:37

【摘要】：如今,国内外大多数油田在采油过程中大量使用各种聚合物,主要包括羟丙基瓜尔胶、聚丙烯酰胺和羧甲基纤维素等,致使大多数油田采出污水中的聚合物含量偏高,部分油田的污水中聚合物质量浓度高达1000mg/L,聚合物含量严重超标,处理难度较大。现在油田现场主要选取的污水处理的方法主要为芬顿氧化法。该方法的优点是氧化活性较高,对聚合物的氧化降解较彻底;氧化降解的产物为无毒、易生物降解的小分子物质,不会产生二次污染;处理过程所需药品价格低廉且易得,处理成本较低。该方法缺点是Fenton氧化过程在pH为2.0~3.0的条件下才能发挥其效能,对反应条件要求较苛刻,而油田污水一般是偏碱性的,所以处理油田污水过程中需要首先调节污水的pH值至2.0~3.0,处理后的污水还需要将pH值回调至6.0~9.0,以满足我国《污水综合排放标准》的相关规定。因此,处理油田污水整个过程需要消耗大量的酸和碱。典型的Fenton体系是在酸性环境下,Fe~(2+)催化H_2O_2快速分解产生大量具有高氧化活性羟基自由基·OH,该体系可用将大多数有机物的氧化降解,应用十分广泛。然而,该体系对污水的酸碱性要求十分苛刻,且使其应用步骤繁琐,使其应用范围受到制约。为了拓宽Fenton法的适用范围,本文制备了一系列金属配合物催化剂,在较高pH条件下催化H_2O_2氧化降解油田常用的聚合物,对拓宽Fenton体系的酸碱性适用范围做了进一步探究。本文主要以羟丙基瓜尔胶的胶液粘度为评价指标,合成了一系列金属配合物催化剂,通过胶液粘度的评价方法,实验筛选出来了5种对双氧水催化效果较好的催化剂,进而对这5种催化剂的最佳应用条件进行了筛选并通过紫外光谱分析对各个催化剂进行了表征以探究其催化效果较好的机理。实验用各催化剂在最佳条件下催化氧化降解油田常用的三种常用聚合物,对比分析了各催化剂对于去除COD和降低粘均分子量的作用效果。取得的主要研究成果如下:(1)筛选出了EDTA-Fe(Ⅱ)、四乙烯五胺-Co、半胱氨酸-Fe(ⅡI)、酒石酸钠-Fe(ⅡI)和邻菲罗啉-Cu等五种催化H_2O_2氧化降解羟丙基瓜尔胶效果较好的催化剂;(2)优化出各催化剂的使用条件如下:EDTA-Fe(Ⅱ)金属离子和配体比例为1:1,双氧水用量为羟丙基瓜尔胶质量的10%,催化剂用量为双氧水物质的量的10%,温度为45℃,pH为9;四乙烯五胺-Co金属离子和配体比例为1:3,双氧水用量为羟丙基瓜尔胶质量的10%,催化剂用量为双氧水物质的量的10%,温度为45℃,pH为7;半胱氨酸-Fe(ⅡI)金属离子和配体比例为1:1,双氧水用量为羟丙基瓜尔胶质量的10%,催化剂用量为双氧水物质的量的10%,温度为45℃,pH为7;酒石酸钠-Fe(ⅡI)金属离子和配体比例为1:3,双氧水用量为羟丙基瓜尔胶质量的10%,催化剂用量为双氧水物质的量的5%,温度为45℃,pH为11;邻菲罗啉-Cu金属离子和配体比例为1:3,双氧水用量为羟丙基瓜尔胶质量的10%,催化剂用量为双氧水物质的量的10%,温度为45℃,pH为11;(3)使用筛选出的5种金属配合物催化剂分别控制在其最优条件下,催化H_2O_2氧化降解油田常用的聚合物羟丙基瓜尔胶、PAM和CMC的模拟胶液。其中EDTA-Fe(Ⅱ)以及邻菲罗啉-Cu催化H_2O_2氧化降解三种聚合物的效果较好,其COD去除率均在99%以上,四乙烯五胺-Co、半胱氨酸-Fe(ⅡI)和酒石酸钠-Fe(ⅡI)催化H_2O_2氧化降解三种聚合物的效果较一般,但也可达到97%以上;(4)紫外光谱和红外光谱表征,证明了金属离子和配体发生了配位生成了配合物,有效的从本质上说明了各催化剂催化效果较好的原因。
[Abstract]:Nowadays, most oilfields at home and abroad use a large number of polymers in the process of oil production, including hydroxypropyl guar gum, polyacrylamide and carboxymethyl cellulose, resulting in high polymer content in the produced sewage of most oilfields. The polymer concentration in the sewage of some oilfields is as high as 1000mg/L, and the polymer content exceeds the standard seriously. Fenton oxidation is the main method of wastewater treatment in oilfield. The advantages of this method are high oxidation activity and thorough oxidative degradation of polymers. The products of oxidative degradation are non-toxic, biodegradable and small molecular substances, which do not cause secondary pollution. The cost of drugs needed in the treatment process is low. The disadvantage of this method is that Fenton oxidation process can only exert its efficiency under the condition of pH 2.0~3.0, and the reaction conditions are more stringent, while oilfield sewage is generally alkaline, so it is necessary to adjust the pH value of the sewage to 2.0~3.0 in the process of treating oilfield sewage, and the treated sewage also needs to return the pH value. Therefore, the whole process of oilfield sewage treatment needs to consume a lot of acid and alkali. A typical Fenton system is in acidic environment, in which Fe~ (2+) catalyzes the rapid decomposition of H_2O_2 to produce a large number of hydroxyl radicals with high oxidation activity. OH can be used to produce most organic compounds. However, the application of this system is very complicated, which restricts its application. In order to broaden the application range of Fenton method, a series of metal complex catalysts were prepared to catalyze the oxidation and degradation of H_2O_2 in oilfields at high pH. In this paper, a series of metal complex catalysts were synthesized with the viscosity of hydroxypropyl guar gum as the evaluation index, and five catalysts with better catalytic effect on hydrogen peroxide were screened out by the method of viscosity evaluation. The optimum application conditions of the catalysts were screened and characterized by UV spectroscopy to explore the mechanism of their better catalytic effect. The catalysts were used to catalyze the oxidation of three commonly used polymers in oilfields under the optimum conditions. The effects of the catalysts on COD removal and viscosity reduction were compared and analyzed. The main results obtained are as follows: (1) Five catalysts, EDTA-Fe (I I), TEA-Co, cysteine-Fe (I I), sodium tartrate-Fe (I I) and o-phenanthroline-Cu, have been screened for the oxidation of hydroxypropyl guar gum by H_2O_2; (2) The optimum conditions for the use of these catalysts are as follows: EDTA-Fe (I I). II) The ratio of metal ions to ligands is 1:1, the amount of hydrogen peroxide is 10% of hydroxypropyl guar gum, the amount of catalyst is 10% of hydrogen peroxide, the temperature is 45 C, the pH is 9, the ratio of metal ions to ligands is 1:3, the amount of hydrogen peroxide is 10% of hydroxypropyl guar gum, and the amount of catalyst is 1% of hydrogen peroxide. The ratio of cysteine to Fe (I I) metal ions and ligands is 1:1, the amount of hydrogen peroxide is 10% of hydroxypropyl guar gum, the amount of catalyst is 10% of hydrogen peroxide, the temperature is 45 C and the pH is 7, the ratio of metal ions to ligands of sodium tartrate to Fe (I I) is 1:3, and the amount of hydrogen peroxide is 10% of hydroxypropyl guar gum. Catalyst dosage is 5% of hydrogen peroxide, temperature is 45 C, pH is 11; metal ion and ligand ratio of o-phenanthroline-Cu is 1:3, hydrogen peroxide dosage is 10% of hydroxypropyl guar gum, catalyst dosage is 10% of hydrogen peroxide, temperature is 45 C, pH is 11; (3) The five metal complexes are controlled respectively by using the selected catalysts. Under the optimum conditions, hydroxypropyl guar gum, PAM and CMC were used to catalyze the oxidation of H_2O_2. EDTA-Fe (I I) and o-phenanthroline-Cu were used to catalyze the oxidation of H_2O_2 to degrade the three polymers. The removal rates of COD were all above 99%, tetraethylenepentamine-Co, cysteine-Fe (I I) and sodium tartrate-Fe (I I). (4) UV and IR spectra showed that metal ions and ligands coordinated to form complexes, which effectively explained the reasons of the better catalytic effect of the catalysts.
【学位授予单位】：西安石油大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TE39

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