Active Machine Learning for Chemical Engineers:A Bright Future Lies Ahead!

By combining machine learning with the design of experiments,thereby achieving so-called active machine learning,more efficient and cheaper research can be conducted.Machine learning algorithms are more flexible and are better than traditional design of experiment algorithms at investigating processes spanning all length scales of chemical engineering.While active machine learning algorithms are maturing,their applications are falling behind.In this article,three types of challenges presented by active machine learning—namely,convincing the experimental researcher,the flexibility of data creation,and the robustness of active machine learning algorithms—are identified,and ways to overcome them are discussed.A bright future lies ahead for active machine learning in chemical engineering,thanks to increasing automation and more efficient algorithms that can drive novel discoveries.

Artificial Intelligence in Steam Cracking Modeling: A Deep Learning Algorithm for Detailed Effluent Prediction

Chemical processes can bene t tremendously from fast and accurate ef uent composition prediction for plant design, control, and optimization. The Industry 4.0 revolution claims that by introducing machine learning into these elds, substantial economic and environmental gains can be achieved. The bottleneck for high-frequency optimization and process control is often the time necessary to perform the required detailed analyses of, for example, feed and product. To resolve these issues, a framework of four deep learning arti cial neural networks (DL ANNs) has been developed for the largest chemicals production process steam cracking. The proposed methodology allows both a detailed characterization of a naphtha feedstock and a detailed composition of the steam cracker ef uent to be determined, based on a limited number of commercial naphtha indices and rapidly accessible process characteristics. The detailed char- acterization of a naphtha is predicted from three points on the boiling curve and paraf ns, iso-paraf ns, ole ns, naphthenes, and aronatics (PIONA) characterization. If unavailable, the boiling points are also estimated. Even with estimated boiling points, the developed DL ANN outperforms several established methods such as maximization of Shannon entropy and traditional ANNs. For feedstock reconstruction, a mean absolute error (MAE) of 0.3 wt% is achieved on the test set, while the MAE of the ef uent predic- tion is 0.1 wt%. When combining all networks using the output of the previous as input to the next the ef uent MAE increases to 0.19 wt%. In addition to the high accuracy of the networks, a major bene t is the negligible computational cost required to obtain the predictions. On a standard Intel i7 processor, predictions are made in the order of milliseconds. Commercial software such as COILSIM1D performs slightly better in terms of accuracy, but the required central processing unit time per reaction is in the order of seconds. This tremendous speed-up and minimal accuracy loss make the presented framework highly suitable for the continuous monitoring of dif cult-to-access process parameters and for the envi- sioned, high-frequency real-time optimization (RTO) strategy or process control. Nevertheless, the lack of a fundamental basis implies that fundamental understanding is almost completely lost, which is not always well-accepted by the engineering community. In addition, the performance of the developed net- works drops signi cantly for naphthas that are highly dissimilar to those in the training set.

Machine Learning in Chemical Engineering:Strengths,Weaknesses,Opportunities,and Threats

Chemical engineers rely on models for design,research,and daily decision-making,often with potentially large financial and safety implications.Previous efforts a few decades ago to combine artificial intelligence and chemical engineering for modeling were unable to fulfill the expectations.In the last five years,the increasing availability of data and computational resources has led to a resurgence in machine learning-based research.Many recent efforts have facilitated the roll-out of machine learning techniques in the research field by developing large databases,benchmarks,and representations for chemical applications and new machine learning frameworks.Machine learning has significant advantages over traditional modeling techniques,including flexibility,accuracy,and execution speed.These strengths also come with weaknesses,such as the lack of interpretability of these black-box models.The greatest opportunities involve using machine learning in time-limited applications such as real-time optimization and planning that require high accuracy and that can build on models with a self-learning ability to recognize patterns,learn from data,and become more intelligent over time.The greatest threat in artificial intelligence research today is inappropriate use because most chemical engineers have had limited training in computer science and data analysis.Nevertheless,machine learning will definitely become a trustworthy element in the modeling toolbox of chemical engineers.

Poisoning effect of polyvinyl chloride on the catalytic pyrolysis of mixed plastics over zeolites

Nowadays,the chemical recycling is applied for only 1%of total waste plastics,largely due to contaminants in plastic waste and difficulty in product control.As the major contaminant,polyvinyl chloride(PVC)often forms corrosive hydrogen chloride(HCl)during the chemical recycling,which may cause severe catalyst deactivation and equipment damage.However,the investigation on catalytic pyrolysis(the major route for plastics chemical recycling)of the PVC containing mixed plastics has been rarely reported.Here,catalytic co-pyrolysis of PVC and polyethylene(PE)was studied over an aromatization catalyst,Pt/ZSM-5,since the basic building block aromatics are desired products from plastics chemical recycling.The poisoning effect of PVC vapor on the catalyst stability was explored by collective efforts of thorough product analysis and catalyst characterization.It was found that the HCl evolving from PVC has an autocatalytic effect that promotes the scission of dehydrochlorinated PVC,resulting in the high yield of benzene and acetylene from PVC.On the other hand,the presence of PVC suppressed the aromatics formation from PE,largely due to the poisoning effect of PVC-derived HCl on the Pt/ZSM-5.The deactivation is irreversible as evidenced by the decreased zeolite crystallinity and the loss of strong acid sites that are key to the aromatization,possibly due to the removal of framework Al upon the interaction with HCl.The modification with octadecylphosphonic acid only slightly alleviated the PVC poisoning effect.The insights on the PVC poisoning of zeolite catalysts provided in this work may guide the process design of chemical recycling of PVC containing waste plastics.