Heterogeneous Emulsion Catalysis: Transesterification using Amphiphilic Catalysts in Nanoemulsion Environments

Fernando酯交换（或酯化）是化学工业中广泛使用的化学反应。目前使用的均相（液体）催化剂受到下游产物分离困难的困扰，这导致了对非均相（固体）催化剂的探索。然而，由于分别对应于不混溶的甘油三酯/醇/催化剂相的液/液/固（L/L/S）界面中的传质限制，使用多相催化仍然是一个挑战。本研究拟利用多相乳化催化这一新现象来克服L/L/S多相催化反应的传质瓶颈。智力优势：我们的方法是解决不混溶的L/L系统所表现出的传质限制，同时改善下游催化剂的分离问题，通过开发一种非均相催化剂，作为乳化剂（两亲物），这基本上将被定位在两种不混溶的液体之间的界面。根据我们的概念，两亲性催化剂首先将两种亲水性和疏水性液体分子聚集在一起，并且由于催化剂的乳化特性，使乳液稳定。同时，催化剂将提供其活性位点用于发生反应（在这种情况下为酯交换）。当催化剂在反应后被分离时，乳液失去其稳定性并且将聚结成现在的产物，分别为亲水性和疏水性液体的脂肪酸甲酯和甘油。这个过程，逃避我们的注意力，可能会打开一个新的催化剂和催化过程，可以传播到许多应用，包括生物可再生能源生产线。我们已经通过一系列初步研究证明了这一概念是可行的，这些研究已经产生了一些同行评审的出版物。在这些研究期间，我们观察到，当经受超声处理时，单体、二聚体、三聚体和四聚体形式的异丙醇钛有助于形成稳定的纳米乳液。这些体系的进一步反应产生脂肪酸乙酯，与常规混合体系相比，一些表现出高于133%的产率增加。这种非均相两亲-催化杂化无机聚合物的概念是新颖的，并且在这种催化体系的几乎每个方面都存在知识空白。这个概念的美妙之处在于通过控制溶液中水的量来控制非均相催化剂颗粒的尺寸的能力，这极大地帮助测试我们的中心假设，即，部分聚合的金属醇盐在酯交换反应中充当多相两亲催化剂。该假设背后的基本原理是纳米乳液的大表面积将提供高反应速率。我们计划研究的基本科学问题是两亲性多相催化剂如何在这样的纳米乳液环境中发挥作用。本申请的目的是：1.评价粒径（金属异丙氧化物低聚）、组分浓度和超声参数对纳米乳液形成和稳定性的影响。测定金属异丙氧化物的低聚对脂肪酸甲酯产率的影响。更广泛的影响：这一创新性和创造性的工作将产生巨大的经济和环境效益，除了推进我们目前对乳液催化相关科学的理解。一个主要的教育目标是通过一种名为“应用为中心的培训”（ACT）的创新技术将研究融入教育，该技术使学生在本科生涯的早期就接触到真实的世界工程问题。该计划预计将介绍科学，数学和工程之间的联系，并解决当今工程教育面临的几个问题。研究经验下实现学生（REUAS）是PI想实验的概念，少数民族和代表性不足的学生谁是学术风险（2.5 GPA和26标准ACT成绩）将提供研究机会早在他们的本科课程。这些学生的进展将在他们的本科生涯的过程中进行跟踪，以评估是否暴露他们到实际研究帮助他们恢复对工程教育和学位课程的兴奋。

CBET-0827514 FernandoTransesterification (or esterification) is a widely used chemical reaction in the chemical industry. Presently used homogeneous (liquid) catalysis is plagued with downstream product separation difficulties which has led the quest for heterogeneous (solid) catalysts. However, using heterogeneous catalysis is still a challenge due to mass transfer limitations in liquid/liquid/solid (L/L/S) interface corresponding to immiscible triglyceride/alcohol/catalyst phases, respectively. This proposal intends to use a novel phenomenon, heterogeneous emulsion catalysis, to remove the mass transfer bottleneck of L/L/S heterogeneous catalytic reactions. Intellectual Merit: Our approach is to address mass transfer limitations exhibited by immiscible L/L systems while ameliorating downstream catalysts separation issues by developing a heterogeneous catalyst that acts as an emulsifier (amphiphile) which essentially will be positioned at the interface between the two immiscible liquids. According to our concept, the amphiphilic catalyst first brings the two hydrophilic and hydrophobic liquid molecules together and due to the emulsification properties of the catalyst, stabilizes the emulsion. In the mean time, the catalyst will lend its active sites for the reaction (in this case transesterification) to occur. When the catalyst is separated after reaction, the emulsion loses its stability and will coalesce to, now the products, fatty acid methyl esters and glycerol which are hydrophilic and hydrophobic liquids, respectively. This process that has eluded our attention may open up a new line of catalysts and catalytic processes that may be propagated to many applications including biorenewable energy production. We have proven that this concept is feasible via a series of preliminary studies that have already resulted in a couple of peer reviewed publications. During these studies, we observed that titanium isopropoxide in its monomeric, dimeric, trimeric and tetrameric forms helped formation of stable nanoemulsions when subjected to ultrasonication. Further reaction of these systems resulted in fatty acid ethyl esters with some exhibiting above 133% yield increase as compared to conventionally mixed systems. This concept of heterogeneous amphiphilic-catalytic hybrid inorganic polymers is novel and there is a knowledge gap in just about every aspect of such a catalytic system. The beauty of this concept is the ability to control the size of the heterogeneous catalyst particles by controlling the amount of water in the solution which immensely helps testing our central hypothesis, i.e., partially polymerized metal alkoxides acts as heterogeneous amphiphilic catalysts in transesterification reactions. The rationale behind this hypothesis is that the large surface area of the nanoemulsions will provide for high reaction rates. The fundamental scientific question we plan investigate is how an amphiphilic heterogeneous catalyst will function in such a nanoemulsion environment. The objectives of this application are to: 1. Evaluate the effect of particle size (metal isopropoxide oligomerization), component concentration and ultrasonic parameters on formation and stability of nanoemulsions and 2. Determine the effect of oligomerization of metal isopropoxides on fatty acid methyl esters yield. Broader Impacts: This innovative and creative work will generate enormous economical and environmental benefits in addition to advancing our present understanding of science related to emulsion catalysis. A major educational objective is to integrate research into education via an innovative technique named "Application Centered Training" (ACT) which engages students early in their undergraduate career with real world engineering problems. This program is expected to introduce the nexus between science, math and engineering and address several issues engineering education faces today. Research Experience for Under Achieving Students (REUAS) is a concept the PI would like to experiment where minority and under represented students who are academically at risk (2.5 GPA and 26 standard ACT scores) will be provided with research opportunities early in their undergraduate program. The progress of these students will be tracked during the course of their undergraduate career to evaluate whether exposing them into practical research helps them resuscitate their excitement towards engineering education and the degree program.