Vol.:(0123456789) Brazilian Journal of Chemical Engineering (2020) 37:691–701 https://doi.org/10.1007/s43153-020-00067-1 1 3 ORIGINAL PAPER Producing gasoline‑like hydrocarbons by cracking crude soybean oil: tuning the NaZSM‑5 zeolite’s acidity for increasing the catalyst lifetime Carlos A. Ortiz‑Bravo 1  · Cassio H. Zandonai 2  · Mara Heloisa N. Olsen‑Scaliante 2  · Nádia Regina Camargo Fernandes 2 Received: 16 May 2020 / Revised: 17 August 2020 / Accepted: 19 August 2020 / Published online: 28 August 2020 © Associação Brasileira de Engenharia Química 2020 Abstract This work investigates the efect of NaZSM-5 zeolite’s acid properties on the catalytic cracking of crude soybean to produce gasoline-like hydrocarbons. We modifed both the acid concentration and the acid strength of the NaZSM-5(60) zeolite (where 60 denotes the SiO 2 /Al 2 O 3 molar ratio) either by varying the SiO 2 /Al 2 O 3 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 SiO 2 /Al 2 O 3 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. Keywords Biofuels · Catalytic cracking · Vegetable oil · ZSM-5 zeolite · Coke Introduction With the fluctuating prices of crude oil and increasing greenhouse emissions, developing renewable fuels has gained growing attention in the past years. Among renew- able energy resources, biofuels obtained from processing vegetable oils are a good alternative because they decrease greenhouse gas emissions compared with conventional fos- sil fuels (Wang and Tao 2016). Thus, the global trend in the eventual environmental crisis advocates for developing crop systems without compromising either the food security or the integrity of the ecosystems. In this context, Brazil is currently the second-largest producer of soybeans on the international stage, reporting 32% of world production in 2019, as reported by the EMBRAPA (Empresa Brasileira de Pesquisa Agropecuária and Ministério da Agricultura 2019). Therefore, the high soybean oil production ensures its use for energy purposes. Currently, vegetable oils, even soybean, are being con- verted through diferent processes like pyrolysis, gasifca- tion, and esterifcation-transesterifcation for energy pur- poses. The latter is traditionally used to produce biodiesel (Fatty Acid Methyl Esters, FAMEs). However, biodiesel is a limited fuel because it presents low miscibility, oxidative instability, and defcient cold-fow properties. Moreover, the industrial deployment of biodiesel requires the implemen- tation of a new infrastructure diferent from those used in conventional oil refning (Issariyakul and Dalai 2014; Naik et al. 2010). Therefore, in the past years, biodiesel has been used for producing value-added compounds rather than for energetic purposes (Knothe 2010). Conversely, vegetable Electronic supplementary material The online version of this article (https://doi.org/10.1007/s43153-020-00067-1) contains supplementary material, which is available to authorized users. * Carlos A. Ortiz-Bravo carlos.ortiz0511@gmail.com 1 Chemical Engineering Program, Federal University of Rio de Janeiro, Rio de Janeiro, RJ 1941-972, Brazil 2 Chemical Engineering Department, State University of Maringa, Maringa, PR 87020-900, Brazil