Carlos A. Ortiz-Bravo

Bio: Carlos A. Ortiz-Bravo is an academic researcher from Federal University of Rio de Janeiro. The author has contributed to research in topics: Fluid catalytic cracking & Gasoline. The author has an hindex of 3, co-authored 4 publications receiving 63 citations.

Producing gasoline-like hydrocarbons by cracking crude soybean oil: tuning the NaZSM-5 zeolite’s acidity for increasing the catalyst lifetime

Abstract: This work investigates the effect of NaZSM-5 zeolite’s acid properties on the catalytic cracking of crude soybean to produce gasoline-like hydrocarbons. We modified both the acid concentration and the acid strength of the NaZSM-5(60) zeolite (where 60 denotes the SiO2/Al2O3 molar ratio) either by varying the SiO2/Al2O3 ratio (i.e., 30, and 90) or by exchanging the compensation cation (i.e., from Na+ to H+). Given the ammonia temperature-programmed desorption and temperature-programmed oxidation tests, we observed that the acid strength of the catalyst is associated not only with the distribution of the cracking products, but also with the nature of the carbonaceous deposits formed during the reaction. Weak, medium, and strong acidity were associated with the formation of heavy hydrocarbon species, soft, and hard coke, respectively. The NaZSM-5 zeolites exhibited weak and medium acidity, while the HZSM-5(60) zeolite exhibited weak and strong acidity. Although both NaZSM-5(30) and HZSM-5(60) zeolites delivered higher gasoline yield than the NaZSM-5(60) zeolite due to its higher acid concentration, the HZSM-5(60) zeolite formed carbonaceous deposits with lower reactivity (i.e., hard coke). Therefore, low values of SiO2/Al2O3 ratio in the NaZSM-5 zeolite drive the reaction products towards gasoline-like hydrocarbons and favor the catalyst reactivation through the formation of more reactive carbonaceous deposits.

Catalytic hydrodeoxygenation of triglycerides: An approach to clean diesel fuel production

Abstract: The catalytic upgrading of vegetable oil to green diesel is one of the distinct research subjects in biorefineries. The catalytic conversion of triglycerides entails the method of hydrotreating such as hydrogenation, hydrodeoxygenation, decarboxylation and decarbonylation as well as isomerization. The product derived is renewable green diesel (straight chain hydrocarbon), of which its production addresses the sustainability of the future energy. The main challenges faced by hydrodeoxygenation are the selection and synthesis of suitable catalysts, selection of appropriate feedstocks, optimization of the thermodynamic parameters, and the reaction pathways. The literature on the selection of feedstock and model compounds is discussed in the sub-section. This review also includes the evaluation on several potential catalysts such as bimetallic solid acid, sulphided, non-sulphided, nitrides, phosphided, isomerization and hydrocracking catalysts as well as the noble metal catalysts. The selection of the metal supports catalysts, the catalyst designed practice and the overall performance is also reviewed and discussed. The most common supports used for the hydrodeoxygenation is solid acid composites such as Al 2 O 3 and zeolites. In addition, the promoters tested yield different results with different reaction mechanisms demonstrated. The research on the hydrodeoxygenation pathways and the product distribution related with all kinds of catalysts are also addressed. In addition, the advancement of co-hydroprocessing of mix-vegetable oil and vacuumed gas oil is addressed and summarized as well. Overall, this review provides a comprehensive discussion on the hydrodeoxygenation issues and challenges in all relevant technical aspects.

Strategies to Enhance the Catalytic Performance of ZSM-5 Zeolite in Hydrocarbon Cracking: A Review

Abstract: ZSM-5 zeolite is widely used in catalytic cracking of hydrocarbon, but the conventional ZSM-5 zeolite deactivates quickly due to its simple microporous and long diffusion pathway. Many studies have been done to overcome these disadvantages recently. In this review, four main approaches for enhancing the catalytic performance, namely synthesis of ZSM-5 zeolite with special morphology, hierarchical ZSM-5 zeolite, nano-sized ZSM-5 zeolite and optimization of acid properties, are discussed. ZSM-5 with special morphology such as hollow, composite and nanosheet structure can effectively increase the diffusion efficiency and accessibility of acid sites, giving high catalytic activity. The accessibility of acid sites and diffusion efficiency can also be enhanced by introducing additional mesopores or macropores. By decreasing the crystal size to nanoscale, the diffusion length can be shortened. The catalytic activity increases and the amount of carbon deposition decreases with the decrease of crystal size. By regulating the acid properties of ZSM-5 with element or compound modification, the overreaction of reactants and formation of carbon deposition could be suppressed, thus enhancing the catalytic activity and light alkene selectivity. Besides, some future needs and perspectives of ZSM-5 with excellent cracking activity are addressed for researchers’ consideration.

Fluid catalytic cracking technology: current status and recent discoveries on catalyst contamination

Abstract: The fluid catalytic cracking (FCC) technology is one of the pillars of the modern petroleum industry which converts the crude oil fractions into many commodity fuels and platform chemicals, such as...