Lik Yin Ng

Challenges and opportunities in computer-aided molecular design ☆

Abstract In this paper, the significant development, current challenges and future opportunities in the field of chemical product design using computer-aided molecular design (CAMD) tools are highlighted. With the gaining of focus on the design of novel and improved chemical products, the traditional heuristic based approaches may not be effective in designing optimal products. This leads to the vast development and application of CAMD tools, which are methods that combine property prediction models with computer-assisted search in the design of various chemical products. The introduction and development of different classes of property prediction methods in the overall product design process is discussed. The exploration and application of CAMD tools in numerous single component product designs, mixture design, and later in the integrated process-product design are reviewed in this paper. Difficulties and possible future extension of CAMD are then discussed in detail. The highlighted challenges and opportunities are mainly about the needs for exploration and development of property models, suitable design scale and computational effort as well as sustainable chemical product design framework. In order to produce a chemical product in a sustainable way, the role of each level in a chemical product design enterprise hierarchy is discussed. In addition to process parameters and product quality, environment, health and safety performance are required to be considered in shaping a sustainable chemical product design framework. On top of these, recent developments and opportunities in the design of ionic liquids using molecular design techniques have been discussed.

A systematic methodology for optimal mixture design in an integrated biorefinery

Abstract Biomass is a sustainable source of energy which can be utilised to produce value-added products such as biochemical products and biomaterials. In order to produce a sustainable supply of such value-added products, an integrated biorefinery is required. An integrated biorefinery is a processing facility that integrates multiple biomass conversion pathways to produce value-added products. To date, various biomass conversion pathways are available to convert biomass into a wide range of products. Due to the large number of available pathways, various systematic screening tools have been developed to address the process design aspect of an integrated biorefinery. Process design however, is often inter-linked with product design as it is important to identify the optimal molecule (based on desired product properties) prior to designing its optimal production routes. In cases where the desired product properties cannot be met by a single component chemical product, a mixture of chemicals would be required. In this respect, product and process design decisions would be a challenging task for an integrated biorefinery. In this work, a novel two-stage optimisation approach is developed to identify the optimal conversion pathways in an integrated biorefinery to convert biomass into the optimal mixtures in terms of target product properties. In the first stage, the optimal mixture is designed via computer-aided molecular design (CAMD) technique. CAMD technique is a reverse engineering approach which predicts the molecules with optimal properties using property prediction models. Different classes of property models such as group contribution (GC) models and quantitative structure property relationship (QSPR) are adapted in this work. The main component of the mixture is first determined from the target product properties. This is followed by the identifying of additive components to form an optimal mixture with the main component based on the desired product properties. Once the optimal mixture is determined, the second stage identifies the optimal conversion pathways via superstructural mathematical optimisation approach. With such approach, the optimal conversion pathways can be determined based on different optimisation objectives (e.g. highest product yield, lowest environmental impact etc.). To illustrate the proposed methodology, a case study on the design of fuel additives as a mixture of different molecules from palm-based biomass is presented. With the developed methodology, optimal fuel additives are designed based on optimal target properties. Once the optimal fuel additives are designed, the optimal conversion pathways in terms of highest product yield and economic performance that convert biomass into the optimal fuel additives are identified.

Robust chemical product design via fuzzy optimisation approach

Abstract Traditionally, the design of new chemical products for specific applications is done by using a combination of design heuristics, experimental studies and expert judgements. In addition to the conventional methods, chemical products can also be designed by using computer-aided molecular design (CAMD) techniques. Based on CAMD, optimal chemical products can be designed by identifying the molecule with the best properties that correspond with the target functionalities of the product. In general, the optimality of product property (termed as property superiority) is the only factor considered while designing optimal products by using CAMD techniques. However, it is noted that property prediction models are developed with certain accuracy and uncertainties. As the accuracy of property prediction models (termed as property robustness) can affect the effectiveness of CAMD techniques in predicting the product property, the effects of property prediction uncertainty have to be considered while applying CAMD techniques. This paper presents a systematic fuzzy optimisation based molecular design methodology. The methodology is developed for the design of optimum molecules used in chemical processes by considering and optimising both property superiority and robustness. Property superiority is quantified by property optimality. Meanwhile, property robustness is expressed by the standard deviation of the property prediction model, which is a measure of average variation between the experimental data and estimated values of product property using property prediction model. Fuzzy optimisation approach is extended in this work to address and trade off property superiority and robustness simultaneously. Molecular design technique is adapted in this work to identify the optimal molecular structure which satisfies multiple product specification. To illustrate the proposed method, a case study is presented where optimal solution is selected based on how much the solution satisfied the criteria of property superiority and robustness.

Optimal Chemical Product Design via Fuzzy Optimisation based Inverse Design Techniques

Abstract While designing optimal products using molecular design technique for a specific application, product superiority is the only factor considered during design. It is noted that the effectiveness of this approach is highly dependent on the model accuracy which represents product robustness. Thus, to design an optimal product efficiently, the effect of property prediction uncertainty has to be addressed. This paper presents a systematic methodology for the design of optimum molecules used in chemical processes by considering both product superiority and robustness. Fuzzy optimisation approach is incorporated into inverse design techniques for this purpose. Inverse product design techniques utilize molecular design techniques to predict the molecular structure of the product from the target properties. Optimal solution is selected based on how much the solution satisfied the criteria of product superiority and robustness. The effectiveness of the developed methodology is shown by a case study on fungicide design, where the designed fungicide possess superior attributes than the conventionally used fungicide.

Chapter 1 – Mathematical Principles of Chemical Product Design and Strategies

Abstract With the transformation of chemical industries from being process-focused to being product-focused, there has been remarkable progress and efforts in the field of computer-aided chemical product design. This chapter provides an overview of the various mathematical tools used for chemical product design. This chapter focuses on the utilization of mathematical programming techniques to identify/generate molecules with optimal/desirable properties. Various optimization algorithms appropriate for dealing with single and multiple objectives are described. In order to utilize such optimization techniques, a discussion of design of experiments that maximizes the collection of information is presented. The data gathered is utilized to develop property models that relate molecular structure to properties and are incorporated in the optimization procedure. A discussion of molecular descriptors, which capture structural features, is also presented. Also, the two main approaches for solving molecular design problems, i.e., the forward approach and the inverse approach, are presented. These methods are compared to the traditional product design approach, which relies primarily on experiments. The consideration of uncertainty in the computer-aided design procedures is also discussed in this chapter. Finally, further development possibilities in the field of chemical product design are discussed.

Systematic Chemical Reaction Pathway Synthesis for Sustainable Integrated Biorefineries

Abstract An integrated biorefinery is a processing facility that converts biomass into value-added products and energy via various conversion technologies. However, due to high number of technologies available, it is a challenge to systematically synthesise a sustainable integrated biorefinery considering economic performance, environmental impact and energy requirement simultaneously. To address this issue, a multi-objective optimisation approach is used in this work to synthesise a sustainable integrated biorefinery. To illustrate the proposed approach, a palm-based biomass case study is solved.

Challenges and opportunities in computer aided molecular design

Abstract In this paper, we highlight the significant developments, current challenges and future opportunities in field of chemical product design using computer aided molecular design tools. With the gaining of focus on the design of performance chemical products, the traditional heuristic based approaches may not be effective in designing optimal products. The introduction and development of property estimation methods in the overall product design process, and later in the integrated process-product design are reviewed in this paper. The highlighted challenges and opportunities are mainly the needs for exploration and development of property models and sustainable chemical product design framework. The latter consider not only the process parameters and product quality, but also environment, health and safety performance. In the last section, recent developments and opportunities in the design of ionic liquids using molecular design techniques have been discussed.

Enterprise Decision-making Framework for Chemical Product Design in Integrated Biorefineries

Biomass utilisation is identified as a promising solution to minimise society’s dependency on fossil fuels for energy generation. By employing the concept of integrated biorefinery, biomass can be converted into power, heat and value-added products in a sustainable and efficient way. To date, biomass can be converted into a spectrum of products with the availability of various biomass conversion pathways. Due to the substantial amount of potential products and conversion technologies, design of chemical products and processing routes in integrated biorefinery has become more challenging. Furthermore, consumer-driven chemical product design has gained magnificent attention in chemical industry, owing to the shifting of market from commodity products to high-value-added products. As a result, the task of chemical product design that is traditionally dedicated to chemists has nowadays become a multifaceted process that requires collective efforts from various fields. In this work, a framework is proposed to facilitate the decision-making involved in the overall chemical product design and production process by integrating four major organisational units of an enterprise: corporate unit, business unit, research and development (R&D) unit and production unit. The corporate unit is responsible for the enterprise goal line setting for the entire chemical product design and production process, the business unit performs detailed analysis on the existing market, the R&D unit is in charge of the design of chemical product that fulfils the customers’ needs while the production unit produces the chemical product. As a whole, the cooperation between these major organisational units of an enterprise design product that fulfils product needs, determines conversion pathways to produce the product from biomass and identifies product demand and price while fulfilling the enterprise goals. To illustrate the proposed methodology, a case study on the design of dry-cleaning solvent from palm-based biomass is presented.

Systematic decision making methodology for chemical product design in integrated biorefineries

Abstract An integrated biorefinery is a processing facility that converts biomass into power, heat and value-added products in a sustainable and efficient way. To date, various biomass conversion pathways are available to convert biomass into a spectrum of products. Due to the substantial amount of potential products and conversion technologies, design of chemical products and processing routes in integrated biorefinery has become more challenging. In addition, consumer-driven chemical product design has gained significant attentions in chemical industry due to the shifting of market from commodity to high-value-added products. Thus, the task of chemical product design that is traditionally dedicated to chemists has nowadays become a multifaceted process that requires collective efforts from various fields. In this work, a decision making methodology that integrates four major organizational units of a company: corporate unit, business unit, research and development unit, and production unit is proposed. By integrating and solving these units, the proposed methodology designs product that fulfils customer requirements, determines conversion pathways that convert biomass into the product, and identifies product demand and price while fulfilling the company’s goals. To illustrate the proposed methodology, a case study on the design of dry cleaning solvent from palm-based biomass is presented.