The Internet of Things (IoT) allows different devices in our daily routines, such as refrigerators, light bulbs and autonomous cars, to be part of the Internet. Accordingly, the amount of data circulating in the network increases. Thus, a secure and reliable IoT environment becomes essential to avoid security vulnerabilities. In IoT, resources are limited and existing security solutions used in the traditional Internet can be ineffective, making data security still a challenge. In this scenario, Blockchain emerges as a promising technology to improve security in IoT, as it enables the recording of data in a decentralized, encrypted and immutable way with the consensus of the network participants in a packet data structure called a block. In Blockchain, the consensus is a protocol responsible for maintaining the state of the network and allowing the addition of new blocks with data. However, many consensus protocols require high computational power and power consumption to solve the mathematical problems that make possible data records in the blocks. Since many devices have low processing power in the IoT environment, developing new consensus approaches is needed to use Blockchain in IoT effectively. Therefore, this paper presents the results of a literature review about the use of Blockchain technology, specifically consensus protocol approaches, in IoT security.